Author: "Olivier Boulle" - Searchworks@Jio Institute Digital Library Search Results

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1. Gate-controlled skyrmion and domain wall chirality

Author: Charles-Elie Fillion, Johanna Fischer, Raj Kumar, Aymen Fassatoui, Stefania Pizzini, Laurent Ranno, Djoudi Ourdani, Mohamed Belmeguenai, Yves Roussigné, Salim-Mourad Chérif, Stéphane Auffret, Isabelle Joumard, Olivier Boulle, Gilles Gaudin, Liliana Buda-Prejbeanu, Claire Baraduc, and Hélène Béa
Subjects: Science
Abstract: A major feature defining the motion of magnetic spin textures is the chirality or ’handedness’ of the spin texture, which in turn depends on the underlying material. Normally it is considered as fixed, but in this article Fillion et al demonstrate control of the chirality of skyrmions in a ferromagnetic multilayer, switching the chirality back and forth using an applied gate voltage.
Published: 2022
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2. Skyrmions in synthetic antiferromagnets and their nucleation via electrical current and ultra-fast laser illumination

Author: Roméo Juge, Naveen Sisodia, Joseba Urrestarazu Larrañaga, Qiang Zhang, Van Tuong Pham, Kumari Gaurav Rana, Brice Sarpi, Nicolas Mille, Stefan Stanescu, Rachid Belkhou, Mohamad-Assaad Mawass, Nina Novakovic-Marinkovic, Florian Kronast, Markus Weigand, Joachim Gräfe, Sebastian Wintz, Simone Finizio, Jörg Raabe, Lucia Aballe, Michael Foerster, Mohamed Belmeguenai, Liliana D. Buda-Prejbeanu, Johan Pelloux-Prayer, Justin M. Shaw, Hans T. Nembach, Laurent Ranno, Gilles Gaudin, and Olivier Boulle
Subjects: Science
Abstract: Skyrmions in synthetic antiferromagnets are appealing for use in future memory and computing devices, combining small size and fast motion, but creating, stabilizing, and observing them remains a challenge. Here, Juge et al demonstrate the stabilization and current and light induced nucleation of skyrmions in a synthetic antiferromagnet, observing the magnetization texture in each layer using X-ray magnetic microscopy.
Published: 2022
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3. Large-scale epitaxy of two-dimensional van der Waals room-temperature ferromagnet Fe5GeTe2

Author: Mário Ribeiro, Giulio Gentile, Alain Marty, Djordje Dosenovic, Hanako Okuno, Céline Vergnaud, Jean-François Jacquot, Denis Jalabert, Danilo Longo, Philippe Ohresser, Ali Hallal, Mairbek Chshiev, Olivier Boulle, Frédéric Bonell, and Matthieu Jamet
Subjects: Materials of engineering and construction. Mechanics of materials, TA401-492, Chemistry, QD1-999
Abstract: Abstract In recent years, two-dimensional van der Waals materials have emerged as an important platform for the observation of long-range ferromagnetic order in atomically thin layers. Although heterostructures of such materials can be conceived to harness and couple a wide range of magneto-optical and magneto-electrical properties, technologically relevant applications require Curie temperatures at or above room temperature and the ability to grow films over large areas. Here we demonstrate the large-area growth of single-crystal ultrathin films of stoichiometric Fe5GeTe2 on an insulating substrate using molecular beam epitaxy. Magnetic measurements show the persistence of soft ferromagnetism up to room temperature in 12 nm-thick films, with a Curie temperature of 293 K, and a weak out-of-plane magnetocrystalline anisotropy. The ferromagnetic order is preserved in bilayer Fe5GeTe2, with Curie temperature decreasing to 229 K. Surface, chemical, and structural characterizations confirm the layer-by-layer growth, 5:1:2 Fe:Ge:Te stoichiometric elementary composition, and single-crystalline character of the films.
Published: 2022
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4. Ultra-Fast and High-Reliability SOT-MRAM: From Cache Replacement to Normally-Off Computing.

Author: Guillaume Prenat, Kotb Jabeur, Pierre Vanhauwaert, Gregory di Pendina, Fabian Oboril, Rajendra Bishnoi, Mojtaba Ebrahimi, Nathalie Lamard, Olivier Boulle, Kevin Garello, Juergen Langer, Berthold Ocker, Marie Claire Cyrille, Pietro Gambardella, Mehdi Baradaran Tahoori, and Gilles Gaudin
Published: 2016
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5. Robust and Programmable Logic-In-Memory Devices Exploiting Skyrmion Confinement and Channeling Using Local Energy Barriers

Author: Naveen Sisodia, Johan Pelloux-Prayer, Liliana D. Buda-Prejbeanu, Lorena Anghel, Gilles Gaudin, Olivier Boulle, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), and ANR-19-P3IA-0003,MIAI,MIAI @ Grenoble Alpes(2019)
Subjects: Condensed Matter - Mesoscale and Nanoscale Physics, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], FOS: Physical sciences, General Physics and Astronomy, Physics - Applied Physics, Applied Physics (physics.app-ph), [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, Hardware_LOGICDESIGN
Abstract: International audience; Magnetic skyrmions are promising candidates for logic-in-memory applications, intrinsically merging high-density nonvolatile data storage with computing capabilities, owing to their nanoscale size, fast motion, and mutual repulsions. However, concepts proposed so far suffer from reliability issues as well as inefficient conversion of magnetic information to electrical signals. In this paper, we propose a logicin-memory device, which exploits skyrmion confinement and channeling using anisotropy energy barriers to achieve reliable data storage and synchronous shift in racetracks combined with cascadable and reprogrammable logics relying purely on magnetic interactions. The device combines a racetrack shift register based on skyrmions confined in nanodots with full-adder (FA) gates. The designed FA is reprogrammable and cascadable and can also be used to perform simple logic operations such as AND, OR, NOT, NAND, XOR, and NXOR. The monolithic design of the logic gate and the absence of any complex electrical contacts makes the device ideal for integration with conventional CMOS circuitry.
Published: 2022

6. Programmable skyrmion logic gates based on skyrmion tunneling

Author: Naveen Sisodia, Johan Pelloux-Prayer, Liliana D. Buda-Prejbeanu, Lorena Anghel, Gilles Gaudin, Olivier Boulle, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), ANR-19-P3IA-0003,MIAI,MIAI @ Grenoble Alpes(2019), and ANR-17-CE24-0045,SKYLOGIC,Manipulation de skyrmions magnétiques pour des applications logique-mémoire(2017)
Subjects: Condensed Matter - Mesoscale and Nanoscale Physics, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], General Physics and Astronomy, FOS: Physical sciences, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, Hardware_LOGICDESIGN
Abstract: International audience; Magnetic skyrmions are promising candidates as elementary nanoscale bits in logic-in-memory devices, intrinsically merging high-density memory and computing capabilities. Here we exploit the dynamics of skyrmions interacting with anisotropy energy barriers patterned by ion irradiation to design programmable logic gates. Using micromagnetic simulations with experimental parameters, we show that a fine tuning of the barrier height and width allows the selective tunneling of skyrmions between parallel nanotracks triggered by skyrmion-skyrmion interaction. This can be leveraged to design a skyrmion demultiplexer logic gate that works solely using skyrmions as logic inputs. By cascading and connecting demultiplexer gates with a specific topology, we develop a fully programmable logic gate capable of producing any possible logic output as a sum of all minterms generated by a given set of inputs without requiring any complex additional electric or magnetic interconversion. The proposed design is fully conservative and cascadable, enabling purely skyrmion-based logic-in-memory devices.
Published: 2022
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7. Static and dynamic properties of 1-kink skyrmion in Pt/Co/MgO trilayer

Author: Liliana D. Buda-Prejbeanu, Ch.-E. Fillion, F. Nasr, Olivier Boulle, Hélène Béa, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), and ANR-19-CE24-0019,ADMIS,Contrôle de l'interaction de Dzyaloshinskii-Moryia par champ électrique(2019)
Subjects: Condensed Matter::Quantum Gases, Materials science, Condensed matter physics, Skyrmion, High Energy Physics::Phenomenology, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 01 natural sciences, 0103 physical sciences, 010306 general physics, 0210 nano-technology, Nonlinear Sciences::Pattern Formation and Solitons, [PHYS.COND.CM-MSQHE]Physics [physics]/Condensed Matter [cond-mat]/Mesoscopic Systems and Quantum Hall Effect [cond-mat.mes-hall]
Abstract: International audience; The 1-kink skyrmion is a topological spin texture composed of a skyrmion having a chiral kink inside its Néel domain wall, this chiral kink being also called domain wall skyrmion. By micromagnetic simulations we have studied the stability of the 1-kink skyrmion as well as its spin-driven dynamics in Pt/Co/MgO. Such trilayer system allows simultaneously the stabilization of various spin textures including skyrmion (Sk, topological charge Q = 1), 1-kink skyrmion (1kSk, Q = 2), and domain wall skyrmion (DWSk, Q = 1). The 1-kink skyrmion is found to be robust against both thermal fluctuations and normally distributed anisotropy for different grainlike region sizes. Such magnetization pattern has a certain resilience to the variation of the Dzyaloshinskii-Moriya interaction and applied magnetic field. The static analysis is complemented with the investigation of the dynamic regime of motion under electrical current. In the limit of moderate injected current the skyrmion and the 1-kink skyrmion behave similarly. However, depending on the geometry of the injected current, the 1-kink skyrmion can be transformed into a single skyrmion or splits in two skyrmions, opening the path to conceive high density logical devices, enabling novel functionalities for logic operations.
Published: 2021

8. Skyrmions in synthetic antiferromagnets and their nucleation via electrical current and ultra-fast laser illumination

Author: Roméo Juge, Naveen Sisodia, Joseba Urrestarazu Larrañaga, Qiang Zhang, Van Tuong Pham, Kumari Gaurav Rana, Brice Sarpi, Nicolas Mille, Stefan Stanescu, Rachid Belkhou, Mohamad-Assaad Mawass, Nina Novakovic-Marinkovic, Florian Kronast, Markus Weigand, Joachim Gräfe, Sebastian Wintz, Simone Finizio, Jörg Raabe, Lucia Aballe, Michael Foerster, Mohamed Belmeguenai, Liliana D. Buda-Prejbeanu, Johan Pelloux-Prayer, Justin M. Shaw, Hans T. Nembach, Laurent Ranno, Gilles Gaudin, Olivier Boulle, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences des Procédés et des Matériaux (LSPM), Université Paris 13 (UP13)-Institut Galilée-Université Sorbonne Paris Cité (USPC)-Centre National de la Recherche Scientifique (CNRS), and ANR-17-CE24-0045,SKYLOGIC,Manipulation de skyrmions magnétiques pour des applications logique-mémoire(2017)
Subjects: Condensed Matter::Quantum Gases, Condensed Matter - Materials Science, Multidisciplinary, Condensed Matter - Mesoscale and Nanoscale Physics, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], General Physics and Astronomy, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, General Chemistry, magnetic skyrmions, magnetism, dynamics, temperature, field, resolution, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, General Biochemistry, Genetics and Molecular Biology
Abstract: Magnetic skyrmions are topological spin textures that hold great promise as nanoscale information carriers in non-volatile memory and logic devices. While room-temperature magnetic skyrmions and their current-induced manipulation were recently demonstrated, the stray field resulting from their finite magnetization as well as their topological charge limit their minimum size and reliable motion in tracks. Antiferromagnetic (AF) skyrmions allow these limitations to be lifted owing to their vanishing magnetization and net zero topological charge, promising room-temperature, ultrasmall skyrmions, fast dynamics, and insensitivity to external magnetic fields. While room-temperature AF spin textures have been recently demonstrated, the observation and controlled nucleation of AF skyrmions operable at room temperature in industry-compatible synthetic antiferromagnetic (SAF) material systems is still lacking. Here we demonstrate that isolated skyrmions can be stabilized at zero field and room temperature in a fully compensated SAF. Using X-ray microscopy techniques, we are able to observe the skyrmions in the different SAF layers and demonstrate their antiparallel alignment. The results are substantiated by micromagnetic simulations and analytical models using experimental parameters, which confirm the chiral SAF skyrmion spin texture and allow the identification of the physical mechanisms that control the SAF skyrmion size and stability. We also demonstrate the local nucleation of SAF skyrmions via local current injection as well as ultrafast laser excitations at zero field. These results will enable the utilization of SAF skyrmions in skyrmion-based devices.
Published: 2021

9. Visibility and Apparent Size of Néel-Type Magnetic Skyrmions in Fresnel Defocus Images of Multilayer Films

Author: Thibaud Denneulin, Jan Caron, Knut Müller-Caspary, Olivier Boulle, András Kovács, Rafal E. Dunin-Borkowski, Ernst Ruska-Zentrum für Mikroskopie und Spektroskopie mit Elektronen (ER-C), Forschungszentrum Jülich GmbH | Centre de recherche de Juliers, Helmholtz-Gemeinschaft = Helmholtz Association-Helmholtz-Gemeinschaft = Helmholtz Association, Department of Chemistry [München], Technische Universität Munchen - Université Technique de Munich [Munich, Allemagne] (TUM), SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)
Subjects: Condensed Matter::Materials Science, Fresnel defocus imaging, multilayers, transmission electron microscopy, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Physics::Optics, ddc:500, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, ferromagnetism, Nonlinear Sciences::Pattern Formation and Solitons, Lorentz microscopy, Néel-type magnetic skyrmions
Abstract: Multilayers that comprise thin films of heavy metals and ferromagnets have been shown to host Néel-type magnetic skyrmions at room temperature. Fresnel defocus imaging in Lorentz transmission electron microscopy is a widely used technique for recording magnetic information about skyrmions. However, the visibility of Néel-type skyrmions in Fresnel defocus images is typically low, both because only a small component of their magnetic field contributes to the signal and because of the presence of diffraction contrast from the polycrystalline multilayer structure. Here, we take advantage of the out-of-plane hysteresis in such samples to record background-subtracted Fresnel defocus images. We demonstrate an improvement in magnetic signal-to-noise ratio and spatial resolution by a factor of 3 for a (Pt/Co/NiFe)×5 multilayer. We also use simulated Fresnel defocus images of Néel-type magnetic skyrmions to understand the influence of defocus on apparent skyrmion size.
Published: 2021

10. Gate-controlled skyrmion and domain wall chirality

Author: Charles-Elie Fillion, Johanna Fischer, Raj Kumar, Aymen Fassatoui, Stefania Pizzini, Laurent Ranno, Djoudi Ourdani, Mohamed Belmeguenai, Yves Roussigné, Salim-Mourad Chérif, Stéphane Auffret, Isabelle Joumard, Olivier Boulle, Gilles Gaudin, Liliana Buda-Prejbeanu, Claire Baraduc, Hélène Béa, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), ANR-16-CE24-0018,ELECSPIN,Dispositifs Spintronique assistés par champ électrique(2016), and ANR-19-CE24-0019,ADMIS,Contrôle de l'interaction de Dzyaloshinskii-Moryia par champ électrique(2019)
Subjects: Condensed Matter - Materials Science, Multidisciplinary, Condensed Matter - Mesoscale and Nanoscale Physics, High Energy Physics::Phenomenology, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], General Physics and Astronomy, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, General Chemistry, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, General Biochemistry, Genetics and Molecular Biology
Abstract: Magnetic skyrmions are localized chiral spin textures, which offer great promise to store and process information at the nanoscale. In the presence of asymmetric exchange interactions, their chirality, which governs their dynamics, is generally considered as an intrinsic parameter set during the sample deposition. In this work, we experimentally demonstrate that a gate voltage can control this key parameter. We probe the chirality of skyrmions and chiral domain walls by observing the direction of their current-induced motion and show that a gate voltage can reverse it. This local and dynamical reversal of the chirality is due to a sign inversion of the interfacial Dzyaloshinskii-Moriya interaction that we attribute to ionic migration of oxygen under gate voltage. Micromagnetic simulations show that the chirality reversal is a continuous transformation, in which the skyrmion is conserved. This control of chirality with 2 - 3 V gate voltage can be used for skyrmion-based logic devices, yielding new functionalities., Comment: 4 figures
Published: 2021

11. Helium Ions Put Magnetic Skyrmions on the Track

Author: Mamour Sall, Kumari Gaurav Rana, Qiang Zhang, Stéphane Auffret, Dominique Mailly, Dafiné Ravelosona, Yves Roussigné, Roméo Juge, Olivier Boulle, Van Tuong Pham, Liliana D. Buda-Prejbeanu, Jan Vogel, Michael Foerster, Kaushik Bairagi, Naveen Sisodia, Gilles Gaudin, Lucia Aballe, M. Belmeguenai, Centre de Nanosciences et de Nanotechnologies (C2N), Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Micro et NanoMagnétisme (MNM), Institut Néel (NEEL), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Matériaux, Défauts et IRradiations (MADIR), Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU), SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), ALBA Synchrotron light source [Barcelone], Laboratoire des Sciences des Procédés et des Matériaux (LSPM), Institut Galilée-Université Sorbonne Paris Cité (USPC)-Centre National de la Recherche Scientifique (CNRS)-Université Sorbonne Paris Nord, Micro et NanoMagnétisme (NEEL - MNM), Spin-Ion Technologies, and ANR-17-CE24-0045,SKYLOGIC,Manipulation de skyrmions magnétiques pour des applications logique-mémoire(2017)
Subjects: Physics, Spintronics, Condensed matter physics, magnetic skyrmions, Perpendicular magnetic anisotropy, Mechanical Engineering, Skyrmion, Track (disk drive), Nucleation, magnetic patterning, racetrack, current-induced dynamics, Bioengineering, 02 engineering and technology, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Helium ions, Hall effect, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], General Materials Science, skyrmion Hall effect, ion-irradiation, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS
Abstract: International audience; Magnetic skyrmions are deemed to be the forerunners of novel spintronic memory and logic devices. While their observation and their current-driven motion at room temperature have been demonstrated, certain issues regarding their nucleation, stability, pinning and skyrmion Hall effect still need to be overcome to realise functional devices. Here we demonstrate that focused He+-ion-irradiation can be used to create and guide skyrmions in racetracks. We show that the weakening of the perpendicular magnetic anisotropy and Dzyaloshinskii-Moriya interaction in the track defined by ion-irradiation leads to the formation of stable isolated skyrmions. Current-driven skyrmion motion experiments and simulations reveal that the skyrmions move along the irradiated track, resulting in a suppression of the skyrmion Hall effect, and that the skyrmion velocity and confinement can be enhanced by tuning the magnetic properties. These results open up a new path to nucleate and guide skyrmions in racetrack devices.
Published: 2021

12. Large-scale epitaxy of two-dimensional van der Waals room-temperature ferromagnet Fe5GeTe2

Author: Mário Ribeiro, Giulio Gentile, Alain Marty, Djordje Dosenovic, Hanako Okuno, Céline Vergnaud, Jean-François Jacquot, Denis Jalabert, Danilo Longo, Philippe Ohresser, Ali Hallal, Mairbek Chshiev, Olivier Boulle, Frédéric Bonell, Matthieu Jamet, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Conception d’Architectures Moléculaires et Processus Electroniques (CAMPE ), SYstèmes Moléculaires et nanoMatériaux pour l’Energie et la Santé (SYMMES), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Département Interfaces pour l'énergie, la Santé et l'Environnement (DIESE), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), ANR-18-CE24-0007,MAGICVALLEY,Polarisation de vallée induite par couplage d'échange magnétique dans les matériaux 2D à grande échelle(2018), ANR-20-CE24-0015,ELMAX,Contrôle électrique de l'aimantation dans les hétérostructures van der Waals épitaxiées(2020), ANR-10-LABX-0051,LANEF,Laboratory of Alliances on Nanosciences - Energy for the Future(2010), ANR-15-IDEX-0002,UGA,IDEX UGA(2015), Institut de Chimie du CNRS (INC)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Condensed Matter - Materials Science, Condensed Matter::Materials Science, Mechanics of Materials, Mechanical Engineering, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, General Materials Science, General Chemistry, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Condensed Matter Physics
Abstract: In recent years, two-dimensional van der Waals materials have emerged as an important platform for the observation of long-range ferromagnetic order in atomically thin layers. Although heterostructures of such materials can be conceived to harness and couple a wide range of magneto-optical and magneto-electrical properties, technologically relevant applications require Curie temperatures at or above room temperature and the ability to grow films over large areas. Here we demonstrate the large-area growth of single-crystal ultrathin films of stoichiometric Fe5GeTe2 on an insulating substrate using molecular beam epitaxy. Magnetic measurements show the persistence of soft ferromagnetism up to room temperature in 12 nm-thick films, with a Curie temperature of 293 K, and a weak out-of-plane magnetocrystalline anisotropy. The ferromagnetic order is preserved in bilayer Fe5GeTe2, with Curie temperature decreasing to 229 K. Surface, chemical, and structural characterizations confirm the layer-by-layer growth, 5:1:2 Fe:Ge:Te stoichiometric elementary composition, and single-crystalline character of the films.
Published: 2021
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13. Extraordinary hall effect in Pt- or Ni-based multilayer stacks with strong perpendicular magnetic anisotropy

Author: Jan, Heinen, Tomek, Schulz, Gerhard, Jakob, Mathias, Kläui, Olivier, Boulle, Gregory, Malinowski, Henk, Swagten, Bert, Koopmans, Christian, Ulysse, Giancarlo, Faini, Berthold, Ocker, Jerzy, Wrona, Sung-Min, Ahn, Ngoc-Minh, Nguyen, and Dafiné, Ravelosona
Published: 2013
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14. Effect of surface roughness on the anomalous Hall effect in Fe thin films

Author: Dongxing Zheng, Yuelei Zhao, Olivier Boulle, Wenbo Mi, Qiang Zhang, Yan Wen, Xixiang Zhang, Aurelien Manchon, Division of Physical Sciences and Engineering (KAUST) (KAUST), King Abdullah University of Science and Technology (KAUST), Tianjin University (TJU), SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)
Subjects: Materials science, Condensed matter physics, Scattering, 02 engineering and technology, Surface finish, 021001 nanoscience & nanotechnology, 01 natural sciences, Condensed Matter::Materials Science, Hall effect, Electrical resistivity and conductivity, 0103 physical sciences, Surface roughness, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Thin film, 010306 general physics, 0210 nano-technology, Order of magnitude, [PHYS.COND.CM-MSQHE]Physics [physics]/Condensed Matter [cond-mat]/Mesoscopic Systems and Quantum Hall Effect [cond-mat.mes-hall], Spin-½
Abstract: Surface roughness plays an important role on the magnetotransport properties of thin films, especially in ultrathin films. In this work, we prepared Fe thin films with various surface roughness by using different seed layers and studied the electrical transport and anomalous Hall effect. By tuning surface roughness scattering, the longitudinal resistivity (${\ensuremath{\rho}}_{xx}$) measured at 5 K increases by one order of magnitude and the corresponding anomalous Hall resistivity (${\ensuremath{\rho}}_{\mathrm{AHE}}$) increases by three times with increasing roughness. The intrinsic, skew-scattering, and side-jump contributions to ${\ensuremath{\rho}}_{\mathrm{AHE}}$ were separated from our data. The anomalous Hall angle depends on the surface roughness, which may be of importance to the material engineering for achieving large spin Hall angle.
Published: 2020

15. Imprint from ferromagnetic skyrmions in an antiferromagnet via exchange bias

Author: Qiang Zhang, Roméo Juge, Kumari Gaurav Rana, Vincent Baltz, Sandra Ruiz-Gómez, Michael Foerster, Van Tuong Pham, Olivier Boulle, Rafael Lopes Seeger, Lucia Aballe, Gilles Gaudin, Mohamed Belmeguenai, Kaushik Bairagi, Stéphane Auffret, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), ALBA Synchrotron light source [Barcelone], Laboratoire des Sciences des Procédés et des Matériaux (LSPM), Institut Galilée-Université Sorbonne Paris Cité (USPC)-Centre National de la Recherche Scientifique (CNRS)-Université Sorbonne Paris Nord, and ANR-17-CE24-0045,SKYLOGIC,Manipulation de skyrmions magnétiques pour des applications logique-mémoire(2017)
Subjects: Condensed Matter - Materials Science, Materials science, Physics and Astronomy (miscellaneous), Condensed matter physics, Spins, Magnetic circular dichroism, Skyrmion, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 01 natural sciences, Magnetic field, Condensed Matter::Materials Science, Exchange bias, Ferromagnetism, 0103 physical sciences, Antiferromagnetism, Condensed Matter::Strongly Correlated Electrons, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, 0210 nano-technology, Spin-½
Abstract: Magnetic skyrmions are topological spin textures holding great potential as nanoscale information carriers. Recently, skyrmions have been predicted in antiferromagnets, with key advantages in terms of stability, size, and dynamical properties over their ferromagnetic analogs. However, their experimental demonstration is still lacking. Here, we show the imprint from ferromagnetic skyrmions into a thin film of an IrMn antiferromagnet, at room temperature and zero external magnetic field, using exchange-bias. Using high-spatial-resolution x-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM), we observed the imprinted spin textures within the IrMn from the XMCD signal of the uncompensated Mn spins at the interface with the ferromagnet. This result opens up a path for logic and memory devices based on skyrmion manipulation in antiferromagnets., Comment: 11 pages, 3 figures
Published: 2020
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16. Room temperature skyrmions at zero field in exchange-biased ultrathin films

Author: Vincent Jacques, Thibaud Denneulin, Aurore Finco, Angela Haykal, Olivier Fruchart, Florentin Fabre, Mohamed Belmeguenai, Rafal E. Dunin-Borkowski, Olivier Boulle, S. Le Denmat, Gilles Gaudin, Philippe David, K. Gaurav Rana, Liliana D. Buda-Prejbeanu, S. Chouaieb, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), Laboratoire Charles Coulomb (L2C), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Optique et microscopies (POM), Institut Néel (NEEL), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Epitaxie et couches minces (EpiCM), Laboratoire des Sciences des Procédés et des Matériaux (LSPM), Université Paris 13 (UP13)-Institut Galilée-Université Sorbonne Paris Cité (USPC)-Centre National de la Recherche Scientifique (CNRS), Ernst Ruska Center for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH | Centre de recherche de Juliers, Helmholtz-Gemeinschaft = Helmholtz Association-Helmholtz-Gemeinschaft = Helmholtz Association, Darpa TEE program, ANR-17-CE24-0025,TOPSKY,Propriétés topologiques des skyrmions magnétiques et opportunitiés pour le dévelopement de nouveaux dispositifs spintroniques(2017), ANR-17-CE24-0045,SKYLOGIC,Manipulation de skyrmions magnétiques pour des applications logique-mémoire(2017), European Project: 639802,H2020,ERC-2014-STG,IMAGINE(2015), European Project: 846597,DIMAF, Optique & Microscopies (NEEL - POM), Epitaxie et couches minces (NEEL- EpiCM), and Ernst Ruska-Zentrum für Mikroskopie und Spektroskopie mit Elektronen (ER-C)
Subjects: Materials science, Magnetometer, General Physics and Astronomy, FOS: Physical sciences, 02 engineering and technology, 01 natural sciences, law.invention, Condensed Matter::Materials Science, Stack (abstract data type), law, 0103 physical sciences, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), ddc:530, Texture (crystalline), 010306 general physics, Spin-½, Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics, Condensed matter physics, Skyrmion, Materials Science (cond-mat.mtrl-sci), 021001 nanoscience & nanotechnology, Magnetic field, Exchange bias, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Magnetic force microscope, 0210 nano-technology
Abstract: We demonstrate that magnetic skyrmions with a mean diameter around 60 nm can be stabilized at room temperature and zero external magnetic field in an exchange-biased Pt/Co/NiFe/IrMn multilayer stack. This is achieved through an advanced optimization of the multilayer stack composition in order to balance the different magnetic energies controlling the skyrmion size and stability. Magnetic imaging is performed both with magnetic force microscopy and scanning Nitrogen-Vacancy magnetometry, the latter providing unambiguous measurements at zero external magnetic field. In such samples, we show that exchange bias provides an immunity of the skyrmion spin texture to moderate external magnetic field, in the tens of mT range, which is an important feature for applications as memory devices. These results establish exchange-biased multilayer stacks as a promising platform towards the effective realization of memory and logic devices based on magnetic skyrmions., Comment: 5 pages, 3 figures
Published: 2020
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17. Controlling Dzyaloshinskii-Moriya Interaction via Chirality Dependent Atomic-Layer Stacking, Insulator Capping and Electric Field

Author: Mairbek Chshiev, Albert Fert, Olivier Boulle, Vincent Cros, Hongxin Yang, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Unité mixte de physique CNRS/Thales (UMPhy CNRS/THALES), THALES-Centre National de la Recherche Scientifique (CNRS), and THALES [France]-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, Stacking, Oxide, FOS: Physical sciences, lcsh:Medicine, 02 engineering and technology, 01 natural sciences, Article, chemistry.chemical_compound, Transition metal, Electric field, 0103 physical sciences, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), 010306 general physics, lcsh:Science, Condensed Matter - Materials Science, Multidisciplinary, Condensed Matter - Mesoscale and Nanoscale Physics, Spintronics, Condensed matter physics, Skyrmion, lcsh:R, Materials Science (cond-mat.mtrl-sci), 021001 nanoscience & nanotechnology, chemistry, Ferromagnetism, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], lcsh:Q, 0210 nano-technology, Rashba effect
Abstract: Using first-principle calculations, we demonstrate several approaches to manipulate Dzyaloshinskii-Moriya Interaction (DMI) in ultrathin magnetic films. First, we find that DMI is significantly enhanced when the ferromagnetic (FM) layer is sandwiched between nonmagnetic (NM) layers inducing additive DMI in NM/FM/NM structures. For instance, as Pt and Ir below Co induce DMI of opposite chirality, inserting Co between Pt (below) and Ir (above) in Ir/Co/Pt trilayers enhances the DMI of Co/Pt bilayers by 15\%. Furthermore, in case of Pb/Co/Pt trilayers (Ir/Fe/Co/Pt multilayers), DMI can be enhanced by 50\% (almost doubled) compared to Co/Pt bilayers reaching a very large DMI amplitude of 2.7 (3.2) meV/atom. Our second approach for enhancing DMI is to use oxide capping layer. We show that DMI is enhanced by 60\% in Oxide/Co/Pt structures compared to Co/Pt bilayers. Moreover, we unveiled the DMI mechanism at Oxide/Co inerface due to interfacial electric field effect, which is different to Fert-Levy DMI at FM/NM interfaces. Finally, we demonstrate that DMI amplitude can be modulated using an electric field with efficiency factor comparable to that of the electric field control of perpendicular magnetic anisotropy in transition metal/oxide interfaces. These approaches of DMI controlling pave the way for skyrmions and domain wall motion-based spintronic applications., Comment: 14 pages, 5 figures
Published: 2018

18. Large-Voltage Tuning of Dzyaloshinskii–Moriya Interactions: A Route toward Dynamic Control of Skyrmion Chirality

Author: Stefania Pizzini, Stéphane Auffret, Gilles Gaudin, Titiksha Srivastava, S. M. Chérif, Laurent Ranno, Anne Bernand-Mantel, Mohamed Belmeguenai, Roméo Juge, Claire Baraduc, Marine Schott, Yves Roussigné, Viola Křižáková, Olivier Boulle, Hélène Béa, Andrey Stashkevich, Mairbek Chshiev, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Micro et NanoMagnétisme (MNM ), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratoire des Sciences des Procédés et des Matériaux (LSPM), Université Paris 13 (UP13)-Institut Galilée-Université Sorbonne Paris Cité (USPC)-Centre National de la Recherche Scientifique (CNRS), ANR-16-CE24-0018,ELECSPIN,Dispositifs Spintronique assistés par champ électrique(2016), Centre National de la Recherche Scientifique (CNRS)-Université Sorbonne Paris Cité (USPC)-Institut Galilée-Université Paris 13 (UP13), and Micro et NanoMagnétisme (NEEL - MNM)
Subjects: skyrmions, Magnetism, perpendicular magnetic anisotropy, chirality, FOS: Physical sciences, Bioengineering, 02 engineering and technology, 01 natural sciences, Dzyaloshinskii−Moriya interaction, electric field effects, Condensed Matter::Materials Science, Electric field, 0103 physical sciences, General Materials Science, 010306 general physics, Anisotropy, Physics, Condensed Matter - Materials Science, Spintronics, Condensed matter physics, Mechanical Engineering, Skyrmion, Materials Science (cond-mat.mtrl-sci), General Chemistry, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Chirality (electromagnetism), Brillouin zone, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Condensed Matter::Strongly Correlated Electrons, 0210 nano-technology, Voltage
Abstract: Electric control of magnetism is a prerequisite for efficient and low power spintronic devices. More specifically, in heavy metal/ ferromagnet/ insulator heterostructures, voltage gating has been shown to locally and dynamically tune magnetic properties like interface anisotropy and saturation magnetization. However, its effect on interfacial Dzyaloshinskii-Moriya Interaction (DMI), which is crucial for the stability of magnetic skyrmions, has been challenging to achieve and has not been reported yet for ultrathin films. Here, we demonstrate 130% variation of DMI with electric field in Ta/FeCoB/TaOx trilayers through Brillouin Light Spectroscopy (BLS). Using polar- Magneto-Optical-Kerr-Effect microscopy, we further show a monotonic variation of DMI and skyrmionic bubble size with electric field, with an unprecedented efficiency. We anticipate through our observations that a sign reversal of DMI with electric field is possible, leading to a chirality switch. This dynamic manipulation of DMI establishes an additional degree of control to engineer programmable skyrmion based memory or logic devices., Comment: 17 pages, 4 figures
Published: 2018

19. Detection of Short-Waved Spin Waves in Individual Microscopic Spin-Wave Waveguides Using the Inverse Spin Hall Effect

Author: Ursula Ebels, Thomas Brächer, Tobias Fischer, Mathieu Fabre, Gilles Gaudin, Olivier Boulle, Stéphane Auffret, Philipp Pirro, Thomas J. Meyer, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Department of Physics and Research Center (OPTIMAS), Technische Universität Kaiserslautern (TU Kaiserslautern), Physics Department and Research Center OPTIMAS, and University of Kaiserslautern
Subjects: Bioengineering, 02 engineering and technology, 01 natural sciences, Spin wave, 0103 physical sciences, General Materials Science, 010306 general physics, ComputingMilieux_MISCELLANEOUS, Physics, Magnonics, Spintronics, Condensed matter physics, Spin polarization, business.industry, Mechanical Engineering, Spin engineering, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], Spin transistor, Spinplasmonics, Spin Hall effect, Optoelectronics, 0210 nano-technology, business
Abstract: The miniaturization of complementary metal–oxide–semiconductor (CMOS) devices becomes increasingly difficult due to fundamental limitations and the increase of leakage currents. Large research efforts are devoted to find alternative concepts that allow for a larger data-density and lower power consumption than conventional semiconductor approaches. Spin waves have been identified as a potential technology that can complement and outperform CMOS in complex logic applications, profiting from the fact that these waves enable wave computing on the nanoscale. The practical application of spin waves, however, requires the demonstration of scalable, CMOS compatible spin-wave detection schemes in material systems compatible with standard spintronics as well as semiconductor circuitry. Here, we report on the wave-vector independent detection of short-waved spin waves with wavelengths down to 150 nm by the inverse spin Hall effect in spin-wave waveguides made from ultrathin Ta/Co8Fe72B20/MgO. These findings open up...
Published: 2017

20. Room-temperature chiral magnetic skyrmions in ultrathin magnetic nanostructures

Author: Stefania Pizzini, Gilles Gaudin, Stéphane Auffret, Hongxin Yang, Jan Vogel, Alessandro Sala, Michael Foerster, Liliana D. Buda-Prejbeanu, Ioan Mihai Miron, Olivier Boulle, Lucia Aballe, Mohamed Belmeguenai, S. M. Chérif, Dayane de Souza Chaves, Andrea Locatelli, Olivier Klein, Mairbek Chshiev, Yves Roussigné, Andrey Stashkevich, Tevfik Onur Menteş, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Micro et NanoMagnétisme (MNM ), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Elettra Sincrotrone Trieste, Laboratoire des Sciences des Procédés et des Matériaux (LSPM), Centre National de la Recherche Scientifique (CNRS)-Université Sorbonne Paris Cité (USPC)-Institut Galilée-Université Paris 13 (UP13), ALBA Synchrotron light source [Barcelone], ANR-14-CE26-0012,ULTRASKY,Skyrmions dans les couches magnétiques ultraminces en vue d'une spintronique basse consommation(2014), Micro et NanoMagnétisme (NEEL - MNM), and Université Paris 13 (UP13)-Institut Galilée-Université Sorbonne Paris Cité (USPC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Nanostructure, Dzyaloshinskii - Moriya interaction, Biomedical Engineering, FOS: Physical sciences, Bioengineering, 02 engineering and technology, Magnetic skyrmion, 01 natural sciences, Condensed Matter::Materials Science, Magnetization, Spin wave, 0103 physical sciences, Perpendicular Magnetic Anisotropy, General Materials Science, Electrical and Electronic Engineering, 010306 general physics, [PHYS.COND.CM-MSQHE]Physics [physics]/Condensed Matter [cond-mat]/Mesoscopic Systems and Quantum Hall Effect [cond-mat.mes-hall], Physics, Condensed Matter - Materials Science, Condensed matter physics, Spintronics, Magnetic circular dichroism, Skyrmion, Materials Science (cond-mat.mtrl-sci), 021001 nanoscience & nanotechnology, Condensed Matter Physics, Atomic and Molecular Physics, and Optics, Magnetic field, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology
Abstract: Magnetic skyrmions are chiral spin structures with a whirling configuration. Their topological properties, nanometer size and the fact that they can be moved by small current densities have opened a new paradigm for the manipulation of magnetisation at the nanoscale. To date, chiral skyrmion structures have been experimentally demonstrated only in bulk materials and in epitaxial ultrathin films and under external magnetic field or at low temperature. Here, we report on the observation of stable skyrmions in sputtered ultrathin Pt/Co/MgO nanostructures, at room temperature and zero applied magnetic field. We use high lateral resolution X-ray magnetic circular dichroism microscopy to image their chiral N\'eel internal structure which we explain as due to the large strength of the Dzyaloshinskii-Moriya interaction as revealed by spin wave spectroscopy measurements. Our results are substantiated by micromagnetic simulations and numerical models, which allow the identification of the physical mechanisms governing the size and stability of the skyrmions., Comment: Submitted version. Extended version to appear in Nature Nanotechnology
Published: 2016

21. Magnetic skyrmions in confined geometries: Effect of the magnetic field and the disorder

Author: Michael Foerster, Sarnjeet S. Dhesi, Eric Gautier, Gilles Gaudin, Alessandro Sala, Liliana D. Buda-Prejbeanu, Tevfik Onur Menteş, Lucia Aballe, Soong-Geun Je, Dayane de Souza Chaves, Jan Vogel, Andrea Locatelli, Stefania Pizzini, Stéphane Auffret, Olivier Boulle, Roméo Juge, Francesco Maccherozzi, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Micro et NanoMagnétisme (MNM ), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), ALBA Synchrotron light source [Barcelone], Elettra Sincrotrone Trieste, IRER - Istituto Regionale di Ricerca della Lombardia, DIAMOND Light source, and Micro et NanoMagnétisme (NEEL - MNM)
Subjects: Nanostructure, FOS: Physical sciences, 02 engineering and technology, Magnetic skyrmion, 01 natural sciences, Condensed Matter::Materials Science, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), 0103 physical sciences, Thin film, 010306 general physics, Anisotropy, ComputingMilieux_MISCELLANEOUS, Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Condensed matter physics, Skyrmion, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Magnetic field, Amplitude, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Nanodot, 0210 nano-technology
Abstract: We report on the effect of the lateral confinement and a perpendicular magnetic field on isolated room-temperature magnetic skyrmions in sputtered Pt/Co/MgO nanotracks and nanodots. We show that the skyrmions size can be easily tuned by playing on the lateral dimensions of the nanostructures and by using external magnetic field amplitudes of a few mT, which allow to reach sub-100 nm diameters. Our XMCD-PEEM observations also highlight the important role of the pinning on the skyrmions size and stability under an out-of-plane magnetic field. Micromagnetic simulations reveal that the effect of local pinning can be well accounted for by considering the thin film grain structure with local anisotropy variations and reproduce well the dependence of the skyrmion diameter on the magnetic field and the geometry., Comment: 17 pages, 4 figures
Published: 2018

22. Spin-orbit torque-induced switching in ferrimagnetic alloys: Experiments and modeling

Author: Daniel Lacour, Mohamed Belmeguenai, Pierre Vallobra, M.-C. Cyrille, Dae-Yun Kim, Juan-Carlos Rojas-Sánchez, Gilles Gaudin, T. Fache, Sug-Bong Choe, Thai Ha Pham, Soong-Geun Je, Olivier Boulle, Stéphane Mangin, Michel Hehn, Gregory Malinowski, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut Jean Lamour (IJL), Université de Lorraine (UL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Seoul National University [Seoul] (SNU), Laboratoire des Sciences des Procédés et des Matériaux (LSPM), Université Paris 13 (UP13)-Institut Galilée-Université Sorbonne Paris Cité (USPC)-Centre National de la Recherche Scientifique (CNRS), IMPACT N4S, ANR-15-IDEX-0004,LUE,Isite LUE(2015), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Electronique et des Technologies de l'Information (CEA-LETI), Université Grenoble Alpes (UGA)-Direction de Recherche Technologique (CEA) (DRT (CEA)), Centre National de la Recherche Scientifique (CNRS)-Université Sorbonne Paris Cité (USPC)-Institut Galilée-Université Paris 13 (UP13), ANR-15-IDEX-04-LUE,LUE,Lorraine Université d'Excellence(2016), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), and Institut de Chimie du CNRS (INC)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, Physics and Astronomy (miscellaneous), Condensed matter physics, Spins, Field (physics), [PHYS.PHYS]Physics [physics]/Physics [physics], 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Magnetization, Ferrimagnetism, 0103 physical sciences, Spin Hall effect, Torque, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, 0210 nano-technology, Current density, ComputingMilieux_MISCELLANEOUS, Spin-½
Abstract: We investigate spin-orbit torque (SOT)-induced switching in rare-earth-transition metal ferrimagnetic alloys using W/CoTb bilayers. The switching current is found to vary continuously with the alloy concentration, and no reduction in the switching current is observed at the magnetic compensation point despite a very large SOT efficiency. A model based on coupled Landau-Lifschitz-Gilbert (LLG) equations shows that the switching current density scales with the effective perpendicular anisotropy which does not exhibit strong reduction at the magnetic compensation, explaining the behavior of the switching current density. This model also suggests that conventional SOT effective field measurements do not allow one to conclude whether the spins are transferred to one sublattice or just simply to the net magnetization. The effective spin Hall angle measurement shows an enhancement of the spin Hall angle with the Tb concentration which suggests an additional SOT contribution from the rare earth Tb atoms.
Published: 2018

23. Creation of Magnetic Skyrmion Bubble Lattices by Ultrafast Laser in Ultrathin Films

Author: Soong-Geun Je, Titiksha Srivastava, Gregory Malinowski, Juan-Carlos Rojas-Sánchez, Michel Hehn, Thai Ha Pham, Olivier Boulle, Gilles Gaudin, Claire Baraduc, Stéphane Auffret, Stéphane Mangin, Hélène Béa, Pierre Vallobra, Institut Jean Lamour (IJL), Institut de Chimie du CNRS (INC)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), This work was supported by the ANR-15-CE24-0009 UMAMI and by the ANR-Labcom Project LSTNM, bythe Institut Carnot ICEEL for the project Optic-switch and Matelas, and by the French PIA project Lorraine Université d’Excellence, Reference ANR-15-IDEX-04-LUE. Experiments were performed using equipment from the TUBE-Daum funded by FEDER (EU), ANR, Région Grand Est and Metropole Grand Nancy. The authors also acknowledgefunding by the French ANR (contract no. ELECSPIN ANR-16-CE24-0018), and by the Nanosciences Foundation (T.S.). Work at the Advanced Light Source was supported by the U.S. Department of Energy (DE-AC02-05CH11231)., IMPACT N4S, ANR-15-IDEX-0004,LUE,Isite LUE(2015), ANR-16-CE24-0018,ELECSPIN,Dispositifs Spintronique assistés par champ électrique(2016), ANR-15-CE24-0009,UMAMI,Comprendre les mécanismes de renversement de l'aimantation induit par excitation laser(2015), and Université de Lorraine (UL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: magnetic skyrmion bubble, Materials science, Bubble, FOS: Physical sciences, Bioengineering, 02 engineering and technology, Magnetic skyrmion, Applied Physics (physics.app-ph), 01 natural sciences, law.invention, law, Lattice (order), 0103 physical sciences, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), General Materials Science, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, ultrafast laser, Nanoscience & Nanotechnology, 010306 general physics, Nonlinear Sciences::Pattern Formation and Solitons, ComputingMilieux_MISCELLANEOUS, skyrmion lattice, Condensed Matter::Quantum Gases, Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics, Spintronics, Condensed matter physics, Mechanical Engineering, Skyrmion, High Energy Physics::Phenomenology, Materials Science (cond-mat.mtrl-sci), Physics - Applied Physics, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Laser, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, Ferromagnetism, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], writing skyrmion, 0210 nano-technology, Ultrashort pulse
Abstract: International audience; Magnetic skyrmions are topologically nontrivial spin textures which hold great promise as stable information carriers in spintronic devices at the nanoscale. One of the major challenges for developing novel skyrmionbased memory and logic devices is fast and controlled creation of magnetic skyrmions at ambient conditions. Here we demonstrate controlled generation of skyrmion bubbles and skyrmion bubble lattices from a ferromagnetic state in sputtered ultrathin magnetic films at room temperature by a single ultrafast (35 fs) laser pulse. The skyrmion bubble density increases with the laser fluence, and it finally becomes saturated, forming disordered hexagonal lattices. Moreover, we present that the skyrmion bubble lattice configuration leads to enhanced topological stability as compared to isolated skyrmions, suggesting its promising use in data storage. Our findings shed light on the optical approach to the skyrmion bubble lattice in commonly accessible materials, paving the road toward the emerging skyrmion-based memory and synaptic devices.
Published: 2018
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24. Thermal Contribution to the Spin-Orbit Torque in Metallic-Ferrimagnetic Systems

Author: Daniel Lacour, Marie-Claire Cyrille, Soong-Geun Je, Thai Ha Pham, Pierre Vallobra, Olivier Boulle, Michel Hehn, Juan-Carlos Rojas-Sánchez, T. Fache, Gilles Gaudin, Stéphane Mangin, Gregory Malinowski, Institut Jean Lamour (IJL), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire d'Electronique et des Technologies de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), IMPACT N4S, ANR-15-IDEX-04-LUE,LUE,Lorraine Université d'Excellence(2016), Université de Lorraine (UL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), ANR-15-IDEX-0004,LUE,Isite LUE(2015), and Institut de Chimie du CNRS (INC)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Condensed Matter - Materials Science, Materials science, Spintronics, Condensed matter physics, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, General Physics and Astronomy, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, 7. Clean energy, 3. Good health, Compensation (engineering), Magnetic field, Non-volatile memory, Condensed Matter::Materials Science, Magnetization, Ferrimagnetism, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0103 physical sciences, Thermal, Curie temperature, 010306 general physics, 0210 nano-technology
Abstract: We report a systematic study of current-induced perpendicular magnetization switching in W/Co$_{x}$Tb$_{1-x}$/Al thin films with strong perpendicular magnetic anisotropy. Various Co$_{x}$Tb$_{1-x}$ ferrimagnetic alloys with different magnetic compensation temperatures are presented. The systems are characterized using MOKE, SQUID and anomalous Hall resistance at different cryostat temperature ranging from 10 K to 350 K. The current-switching experiments are performed in the spin-orbit torque geometry where the current pulses are injected in plane and the magnetization reversal is detected by measuring the Hall resistance. The full reversal magnetization has been observed in all samples. Some experimental results could only be explained by the strong sample heating effect during the current pulses injection. We have found that, for a given composition $x$ and switching polarity, the devices always reach the same temperature $\textit{T}_{switch}(x)$ before switching independently of the cryostat temperature. $\textit{T}_{switch}$ seems to scale with the Curie temperature of the Co$_{x}$Tb$_{1-x}$ ferrimagnetic alloys. This explains the evolution of the critical current (and critical current density) as a function of the alloy concentration. Future application could take advantages of this heating effect which allows reducing the in-plane external field. Unexpected double magnetization switching has been observed when the heat generated by the current allows crosses the compensation temperature., 18 pages, 7 figures. Supplementary: 7 pages, 7 figures
Published: 2018

25. Corrigendum: Room-temperature chiral magnetic skyrmions in ultrathin magnetic nanostructures

Author: Michael Foerster, Tevfik Onur Menteş, Ioan Mihai Miron, Stefania Pizzini, Stéphane Auffret, Liliana D. Buda-Prejbeanu, Yves Roussigné, Olivier Boulle, Jan Vogel, Gilles Gaudin, S. M. Chérif, Hongxin Yang, Andrey Stashkevich, Mohamed Belmeguenai, Dayane de Souza Chaves, Andrea Locatelli, Alessandro Sala, Lucia Aballe, Mairbek Chshiev, and Olivier Klein
Subjects: Nanostructure, Materials science, Condensed matter physics, Skyrmion, Biomedical Engineering, Bioengineering, 02 engineering and technology, Flory–Huggins solution theory, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Atomic and Molecular Physics, and Optics, Ab initio quantum chemistry methods, 0103 physical sciences, Monolayer, General Materials Science, Electrical and Electronic Engineering, 010306 general physics, 0210 nano-technology
Abstract: Nature Nanotechnology 11, 449–454 (2016); published online 25 January 2016; corrected after print 18 July 2017 In the version of this Article originally published, the Dzyaloshinskii–Moriya interaction parameter, D, should have been multiplied by √3. The vertical scale of Fig. 2 has been updated accordingly as has the following sentence concerning D values: “For 5 monolayers (ML) of Co, equivalent to a total Co thickness of 1 nm, the ab initio calculations predict = 4.
Published: 2017

26. Creation of unidirectional spin-wave emitters by utilizing interfacial Dzyaloshinskii-Moriya interaction

Author: Thomas Brächer, Gilles Gaudin, Olivier Boulle, Philipp Pirro, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Department of Physics and Research Center (OPTIMAS), and Technische Universität Kaiserslautern (TU Kaiserslautern)
Subjects: Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Condensed matter physics, FOS: Physical sciences, Model system, 02 engineering and technology, Selective excitation, 021001 nanoscience & nanotechnology, 01 natural sciences, Wavelength, Formalism (philosophy of mathematics), Ferromagnetism, Spin wave, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Condensed Matter::Strongly Correlated Electrons, 010306 general physics, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS, Excitation
Abstract: We present an analytic and numerical study of the creation of a unidirectional spin-wave emission in ultrathin ferromagnetic films sandwiched in an asymmetric layer stack. For this we extend the analytical description of spin waves in spin-wave waveguides by incorporating the influence of the interfacial Dzyaloshinskii-Moriya interaction on the spin-wave propagation. By exploring the model system ${\mathrm{Ni}}_{81}{\mathrm{Fe}}_{19}/\mathrm{Pt}$, we show that it is possible to achieve a unidirectional spin-wave emission by combining wave-vector selective excitation sources with the frequency splitting that arises from the interfacial Dzyaloshinskii-Moriya interaction. Hereby, we focus on device feature sizes and spin-wave wavelengths that are compatible with state-of-the art excitation and detection schemes. We demonstrate that the presented analytical formalism allows for an approximate prediction of the nonreciprocal emission.
Published: 2017

27. Dynamics of magnetic domain walls and skyrmions studied by high resolution XMCD-PEEM microscopy

Author: Stefania Pizzini, Jan Vogel, Nicolas Rougemaille, Fausto Sirotti, Julio Cesar, Dayane Chaves, Onur Mentes, Michael Foester, Lucia Aballe, Andrea Locatelli, and Olivier Boulle
Published: 2016

28. Chiral damping in magnetic domain-walls (Conference Presentation)

Author: Paul Balint, Alain Schuhl, Liliana D. Buda-Prejbeanu, Stéphane Auffret, Olivier Boulle, C. K. Safeer, Ioan Mihai Miron, Emilie Jué, Gilles Gaudin, Alexandre Lopez, Aurelien Manchon, Marc Drouard, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), King Abdullah University of Science and Technology (KAUST), and Gaudin, gilles
Subjects: Physics, Magnetic domain, Condensed matter physics, Magnetism, Skyrmion, media_common.quotation_subject, 01 natural sciences, Asymmetry, [PHYS.COND.CM-MS] Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 010305 fluids & plasmas, Magnetic field, [PHYS.COND.CM-GEN] Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0103 physical sciences, Homogeneous space, Dissipative system, Perpendicular, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 010306 general physics, ComputingMilieux_MISCELLANEOUS, media_common
Abstract: The Dzyaloshinskii-Moriya interaction is responsible for chiral magnetic textures (skyrmions, spin spiral structures, …) in systems with structural inversion asymmetry and high spin-orbit coupling. It has been shown that the domain wall (DW) dynamics in such materials can be explained by chiral DWs with (partly or fully) Neel structure, whose stability derives from an interfacial DMI [1]. In this work, we show that DMI is not the only effect inducing chiral dynamics and demonstrate the existence of a chiral damping [2]. This result is supported by the study of the asymmetry induced by an in-plane magnetic field on field induced domain wall motion in perpendicularly magnetized asymmetric Pt/Co/Pt trilayers. Whereas the asymmetry of the DW motion is consistent with the spatial symmetries expected with the DMI, we show that this asymmetry cannot be attributed to an effective field but originates from a purely dissipative mechanism. The observation of chiral damping, not only enriches the spectrum of physical phenomena engendered by the SIA, but since it can coexist with DMI it is essential for conceiving DW and skyrmion devices. [1] A. Thiaville, et al., EPL 100, 57002 (2012) [2] E. Jue, et al., Nat. Mater., in press (doi: 10.1038/nmat4518)
Published: 2016

29. Impact of Dzyaloshinskii-Moriya interactions on the thermal stability factor of heavy metal/magnetic metal/oxide based nano-pillars

Author: Nikita Strelkov, Bernard Dieny, Olivier Boulle, Liliana D. Buda-Prejbeanu, Paola Tiberto, Paolo Maria Eugenio Icilio Allia, Daniele Gastaldo, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
Subjects: Materials science, Nucleation, Oxide, General Physics and Astronomy, 02 engineering and technology, 01 natural sciences, Metal, Condensed Matter::Materials Science, chemistry.chemical_compound, micromagnetic simulations, 0103 physical sciences, Nano, magnetisation switching, Thermal stability, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010302 applied physics, Condensed matter physics, magnetisation switching, Mimimum Energy path, micromagnetic simulations, 021001 nanoscience & nanotechnology, Mimimum Energy path, Domain wall (magnetism), Ferromagnetism, chemistry, visual_art, visual_art.visual_art_medium, Nanodot, 0210 nano-technology
Abstract: International audience; We studied the thermal stability of ultrathin perpendicular magnetized nanodots in the presence of the Dzyaloshinskii-Moriya interaction (DMI) using a Minimum Energy Path (MEP) method. We find that the smallest energy barrier is associated with the energy path based on domain wall nucleation and propagation down to 25 nm lateral size. We show that the DMI has a detrimental impact on the thermal stability factor of square Pt/Co/AlOx dots, which decreases linearly with the DMI amplitude. Our study reveals that the DMI limits the downscaling of MRAM cells based on heavy metal (HM)/ferromagnet (FM)/oxide trilayers.
Published: 2019

30. Domain wall dynamics in ultrathin Pt/Co/AlOx microstrips under large combined magnetic fields

Author: André Thiaville, Jacques Miltat, Marlio Bonfim, Stanislas Rohart, Joao Sampaio, Emilie Jué, Stefania Pizzini, Liliana D. Buda-Prejbeanu, Ioan Mihai Miron, Stéphane Auffret, Gilles Gaudin, Jan Vogel, Olivier Boulle, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de Physique des Solides (LPS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Micro et NanoMagnétisme (MNM ), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Departamento de Engenharia Elétrica, Universidade Federal do Paraná (UFPR), ANR-11-BS10-0008,ESPERADO,Effets du couple de transfert de spin et des champs Rashba et Oersted sur la dynamique de parois(2011), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), and Micro et NanoMagnétisme (NEEL - MNM)
Subjects: Materials science, Field (physics), Magnetic domain, Condensed matter physics, Dzyaloshinskii - Moriya interaction, domain walls, 02 engineering and technology, Type (model theory), 021001 nanoscience & nanotechnology, 01 natural sciences, magnetic thin films, Magnetic field, Magnetic anisotropy, Domain wall (magnetism), [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0103 physical sciences, Domain (ring theory), Perpendicular, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 010306 general physics, 0210 nano-technology
Abstract: The dynamics of magnetic domain walls in ultrathin strip-patterned Pt/Co/AlOx samples with perpendicular easy axis has been studied experimentally under an easy-axis field, superposed to a hard-axis field oriented along the strip. The easy-axis field is large so that the domain walls move well beyond the creep regime. A chiral effect is observed where the domain wall velocity shows a monotonous and surprisingly large variation with an in-plane field. A micromagnetic analysis, combining analytic, one-dimensional, and two-dimensional simulations with structural disorder, shows that this behavior can be reproduced with a Dzyaloshinskii-Moriya interaction of the interfacial type, with due consideration of the dynamics of the tilt degree of freedom of the domain wall. The estimated effective value of this interaction ($D\ensuremath{\approx}\ensuremath{-}2.2\phantom{\rule{0.28em}{0ex}}\mathrm{mJ}/{\mathrm{m}}^{2}$ for a 0.6 nm Co thickness) is consistent with values obtained by other techniques. It is also shown, by micromagnetic analysis, that several modes and characteristic times occur in the dynamics of the tilt of such domain walls.
Published: 2016
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31. Spin–orbit torque magnetization switching controlled by geometry

Author: Alexandre Lopez, Olivier Boulle, Stefania Pizzini, Stéphane Auffret, Gilles Gaudin, C. K. Safeer, Ioan Mihai Miron, Emilie Jué, Liliana D. Buda-Prejbeanu, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Micro et NanoMagnétisme (NEEL - MNM), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), and Micro et NanoMagnétisme (MNM )
Subjects: Angular momentum, Materials science, Spintronics, Film plane, Biomedical Engineering, Bioengineering, Geometry, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Atomic and Molecular Physics, and Optics, Magnetization, Domain wall (magnetism), Ferromagnetism, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Torque, General Materials Science, Electrical and Electronic Engineering, Electric current, 010306 general physics, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS
Abstract: Magnetization reversal by an electric current is essential for future magnetic data storage technology, such as magnetic random access memories. Typically, an electric current is injected into a pillar-shaped magnetic element, and switching relies on the transfer of spin momentum from a ferromagnetic reference layer (an approach known as spin-transfer torque). Recently, an alternative technique has emerged that uses spin-orbit torque (SOT) and allows the magnetization to be reversed without a polarizing layer by transferring angular momentum directly from the crystal lattice. With spin-orbit torque, the current is no longer applied perpendicularly, but is in the plane of the magnetic thin film. Therefore, the current flow is no longer restricted to a single direction and can have any orientation within the film plane. Here, we use Kerr microscopy to examine spin-orbit torque-driven domain wall motion in Co/AlOx wires with different shapes and orientations on top of a current-carrying Pt layer. The displacement of the domain walls is found to be highly dependent on the angle between the direction of the current and domain wall motion, and asymmetric and nonlinear with respect to the current polarity. Using these insights, devices are fabricated in which magnetization switching is determined entirely by the geometry of the device.
Published: 2016
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32. Shaped angular dependence of the spin-transfer torque and microwave generation without magnetic field

Author: Luis Gustavo Pereira, Frédéric Petroff, Albert Fert, Vincent Cros, Giancarlo Faini, Olivier Boulle, Julie Grollier, Cyrile Deranlot, and Józef Barnaś
Subjects: Physics, Condensed Matter - Materials Science, Spintronics, Condensed matter physics, Field (physics), Spin-transfer torque, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, General Physics and Astronomy, Magnetic field, Magnetization, Torque, Microwave, Nanopillar
Abstract: The generation of oscillations in the microwave frequency range is one of the most important applications expected from spintronics devices exploiting the spin-transfer phenomenon, which is the reorientation of the magnetization of a ferromagnetic domain by spin-polarized current. Here we report transport and microwave power measurements on specially designed nanopillars, for which a non-standard angular dependence of the spin-transfer torque is predicted by theoretical models. We observe a new kind of current-induced dynamics that is characterized by large angle precessions in the absence of any applied field. This is also predicted by simulations including a ‘wavy’ angular dependence of the torque. This type of nanopillar, which is able to generate microwave oscillations in zero applied magnetic field, could represent an interesting method for the implementation of spin-transfer oscillators. We also emphasize the theoretical implications of our results on the angular dependence of the torque.
Published: 2007

33. Ultra-fast three terminal perpendicular spin-orbit torque MRAM (Presentation Recording)

Author: Nathalie Lamard, M. Cubukcu, Berthold Ocker, Pietro Gambardella, Mihai Miron, Kevin Garello, Gilles Gaudin, Claire Hamelin, Liliana D. Buda-Prejbeanu, Juergen Langer, Olivier Boulle, and N. Mikuszeit
Subjects: Condensed Matter::Materials Science, Magnetization, Tunnel magnetoresistance, Magnetoresistive random-access memory, Materials science, Nuclear magnetic resonance, Ferromagnetism, Condensed matter physics, Magnetism, Spin Hall effect, Astrophysics::Solar and Stellar Astrophysics, Spin–orbit interaction, Nanomagnet
Abstract: The discovery that a current flowing in a heavy metal can exert a torque on a neighboring ferromagnet has opened a new way to manipulate the magnetization at the nanoscale. This “spin orbit torque” (SOT) has been demonstrated in ultrathin magnetic multilayers with structural inversion asymmetry (SIA) and high spin orbit coupling, such as Pt/Co/AlOx multilayers. We have shown that this torque can lead to the magnetization switching of a perpendicularly magnetized nanomagnet by an in-plane current injection. The manipulation of magnetization by SOT has led to a novel concept of magnetic RAM memory, the SOT-MRAM, which combines non volatility, high speed, reliability and large endurance. These features make the SOT-MRAM a good candidate to replace SRAM for non-volatile cache memory application. We will present the proof of concept of a perpendicular SOT-MRAM cell composed of a Ta/FeCoB/MgO/FeCoB magnetic tunnel junction and demonstrate ultra-fast (down to 300 ps) deterministic bipolar magnetization switching. Macrospin and micromagnetic simulations including SOT cannot reproduce the experimental results, which suggests that additional physical mechanisms are at stacks. Our results show that SOT-MRAM is fast, reliable and low power, which is promising for non-volatile cache memory application. We will also discuss recent experiments of magnetization reversal in ultrathin multilayers Pt/Co/AlOx by very short (
Published: 2015

34. Ultra-fast perpendicular Spin Orbit Torque MRAM

Author: Gilles Gaudin, Claire Hamelin, Nathalie Lamard, Kevin Garello, V. V. Naletov, Ioan Mihai Miron, Juergen Langer, M. Cubukcu, Liliana D. Buda-Prejbeanu, Thomas Brächer, Olivier Klein, Berthold Ocker, Olivier Boulle, G. de Loubens, N. Mikuszeit, Pietro Gambardella, Marie-Claire Cyrille, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Department of Materials [ETH Zürich] (D-MATL), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Laboratoire Nano-Magnétisme et Oxydes (LNO), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institute of Physics [Kazan] (IoP), Kazan Federal University (KFU), and Singulus technology AG
Subjects: 010302 applied physics, Magnetoresistive random-access memory, Range (particle radiation), Condensed Matter - Materials Science, Materials science, Spintronics, business.industry, Cache memory, MRAM, spin-orbit torque-MRAM (SOT-MRAM), spin transfer, spin-orbit torque, spintronics, spin transfer torque-magnetic random access memory (STT-MRAM), Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, 02 engineering and technology, Nanosecond, 021001 nanoscience & nanotechnology, 01 natural sciences, Electronic, Optical and Magnetic Materials, Tunnel magnetoresistance, Magnetization, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0103 physical sciences, Perpendicular, Torque, Optoelectronics, Electrical and Electronic Engineering, 0210 nano-technology, business
Abstract: We demonstrate ultra-fast (down to 400 ps) bipolar magnetization switching of a three-terminal perpendicular Ta/FeCoB/MgO/FeCoB magnetic tunnel junction. The critical current density rises significantly as the current pulse shortens below 10 ns, which translates into a minimum in the write energy in the ns range. Our results show that SOT-MRAM allows fast and low power write operations, which renders it promising for non-volatile cache memory applications., 15 pages, 3 figures
Published: 2015

35. Chiral damping of magnetic domain walls

Author: C. K. Safeer, Ioan Mihai Miron, Marc Drouard, Aurelien Manchon, Emilie Jué, Alexandre Lopez, Stéphane Auffret, Alain Schuhl, Olivier Boulle, Paul Balint, Liliana D. Buda-Prejbeanu, Gilles Gaudin, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Micro et NanoMagnétisme (MNM ), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), King Abdullah University of Science and Technology (KAUST), and Micro et NanoMagnétisme (NEEL - MNM)
Subjects: Magnetic domain, media_common.quotation_subject, FOS: Physical sciences, 02 engineering and technology, 01 natural sciences, Asymmetry, Physical phenomena, 0103 physical sciences, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Perpendicular, General Materials Science, Multiferroics, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, ComputingMilieux_MISCELLANEOUS, media_common, Physics, Condensed matter physics, Condensed Matter - Mesoscale and Nanoscale Physics, Mechanical Engineering, Skyrmion, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Magnetic field, Mechanics of Materials, Dissipative system, 0210 nano-technology
Abstract: Structural symmetry breaking in magnetic materials is responsible for a variety of outstanding physical phenomena. Examples range from the existence of multiferroics, to current induced spin orbit torques (SOT) and the formation of topological magnetic structures. In this letter we bring into light a novel effect of the structural inversion asymmetry (SIA): a chiral damping mechanism. This phenomenon is evidenced by measuring the field driven domain wall (DW) motion in perpendicularly magnetized asymmetric Pt/Co/Pt trilayers. The difficulty in evidencing the chiral damping is that the ensuing DW dynamics exhibit identical spatial symmetry to those expected from the Dzyaloshinskii-Moriya interaction (DMI). Despite this fundamental resemblance, the two scenarios are differentiated by their time reversal properties: while DMI is a conservative effect that can be modeled by an effective field, the chiral damping is purely dissipative and has no influence on the equilibrium magnetic texture. When the DW motion is modulated by an in-plane magnetic field, it reveals the structure of the internal fields experienced by the DWs, allowing to distinguish the physical mechanism. The observation of the chiral damping, not only enriches the spectrum of physical phenomena engendered by the SIA, but since it can coexists with DMI it is essential for conceiving DW and skyrmion devices.
Published: 2015

36. Spin-orbit torque driven chiral magnetization reversal in ultrathin nanostructures

Author: Olivier Boulle, N. Mikuszeit, I. M. Miron, Liliana D. Buda-Prejbeanu, Kevin Garello, Pietro Gambardella, G. Gaudin, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Department of Materials [ETH Zürich] (D-MATL), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), and European Project: 318144,EC:FP7:ICT,FP7-ICT-2011-8,SPOT(2012)
Subjects: Physics, Length scale, [PHYS]Physics [physics], Condensed Matter - Materials Science, Nanostructure, Condensed matter physics, Condensed Matter - Mesoscale and Nanoscale Physics, Domain-wall dynamics, Nucleation, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Nanomagnet, Electronic, Optical and Magnetic Materials, Magnetic field, Magnetization, Amplitude, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), 0103 physical sciences, Torque, 010306 general physics, 0210 nano-technology
Abstract: International audience; We show that the spin-orbit torque induced magnetization switching in nanomagnets presenting Dzyaloshinskii-Moriya (DMI) interaction is governed by a chiral domain nucleation at the edges. The nucleation is induced by the DMI and the applied in-plane magnetic field followed by domain-wall propagation. Our micromagnetic simulations show that the dc switching current can be defined as the edge nucleation current, which decreases strongly with increasing amplitude of the DMI. This description allows us to build a simple analytical model to quantitatively predict the switching current. We find that domain nucleation occurs down to a lateral size of 25 nm, defined by the length scale of the DMI, beyond which the reversal mechanism approaches a macrospin behavior. The switching is deterministic and bipolar.
Published: 2015

37. Beyond STT-MRAM, Spin Orbit Torque RAM SOT-MRAM for high speed and high reliability applications

Author: Olivier Boulle, Gilles Gaudin, Gregory Di Pendina, Guillaume Prenat, Kotb Jabeur, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Université Grenoble Alpes (UGA), Weisheng Zhao, Guillaume Prenat, Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)
Subjects: Computer science, Technology Node, 02 engineering and technology, Integrated circuit, Nanosecond Time Scale, Longitudinal Magnetic Field, 01 natural sciences, 7. Clean energy, law.invention, law, Universal memory, 0103 physical sciences, Magnetic Tunnel Junction, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, 010302 applied physics, Magnetoresistive random-access memory, Hardware_MEMORYSTRUCTURES, business.industry, Reading (computer), Electrical engineering, 021001 nanoscience & nanotechnology, Resistive random-access memory, CMOS, Memory Hierarchy, Ferroelectric RAM, Dynamic demand, 0210 nano-technology, business
Abstract: International audience; For 40 years, microelectronics has been following the Moore’s law, stating that the density and speed of integrated circuits would double every 18 months. However, this trend is presently getting out of breath, because of incoming insurmountable physical limits. Due to decreasing devices size, leakage current is becoming the main contributor to power dissipation of CMOS. Furthermore, the increased density and reduction in die size lead to heat dissipation and reliability issues. Moreover, the dynamic power keeps on growing up with both clock frequency and global capacitance while the power supply is not scaled down accordingly. Several solutions are investigated to try to push forward these limits at technology, circuit or architecture levels. The “more than Moore” concept consists in using new devices beside or in replacement of standard CMOS transistors. For instance, the use of non-volatile devices is seen as a promising solution to reduce power consumption, improve reliability and offer new functionalities. Several technologies are intensively investigated like Phase Change Random Access Memory (PCRAM), Ferroelectric RAM (FeRAM), RedoxRAM (ReRAM) and Magnetic RAM (MRAM). In its 2010 report, ITRS identified RedoxRAM and STT-MRAM as the two most promising technologies for embedded memories at technology nodes below 16 nm. The combination of non-volatility, fast access time and endurance in MRAM technology paves the path toward a universal memory. Although an expanding attention is given to two-terminal Magnetic Tunnel Junctions (MTJ) with writing based on Spin-Transfer Torque (STT) switching as the potential candidate for future memories, it suffers from weaknesses. Indeed, two main shortcomings are still limiting the reliability and endurance of STT-MRAMs: i) The high current density required for writing can occasionally damage the MTJ barrier, specially for switching on the nanosecond time scale ii) It remains a challenge to fulfill a reliable reading without ever causing switching for very advanced technology nodes, since writing and reading operations share the same path, through the junction. Indeed, the smaller the MTJ the lower the writing current without having the possibility to reduce the reading current to maintain a reliable sensing. Three-terminal MTJ with writing based on Spin-Orbit Torque (SOT) approach revitalizes the hope of an ultimate RAM. It represents a pioneering way to triumph over current two-terminal MTJ’s limitations by separating the reading and the writing paths, completely avoiding tunnel barrier damaging and read disturb issues.
Published: 2015

38. Ultrafast magnetization switching by spin-orbit torques

Author: Abhijit Ghosh, Manuel Baumgartner, Ioan Mihai Miron, Pietro Gambardella, Stéphane Auffret, Olivier Boulle, Can Onur Avci, Gilles Gaudin, Kevin Garello, Department of Materials [ETH Zürich] (D-MATL), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
Subjects: 010302 applied physics, Physics, Physics and Astronomy (miscellaneous), Condensed matter physics, Condensed Matter - Mesoscale and Nanoscale Physics, Nucleation, Pulse duration, FOS: Physical sciences, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Magnetization, Amplitude, Ferromagnetism, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0103 physical sciences, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Single domain, 0210 nano-technology, Ultrashort pulse, ComputingMilieux_MISCELLANEOUS, Spin-½
Abstract: Spin-orbit torques induced by spin Hall and interfacial effects in heavy metal/ferromagnetic bilayers allow for a switching geometry based on in-plane current injection. Using this geometry, we demonstrate deterministic magnetization reversal by current pulses ranging from 180~ps to ms in Pt/Co/AlOx dots with lateral dimensions of 90~nm. We characterize the switching probability and critical current $I_c$ as function of pulse length, amplitude, and external field. Our data evidence two distinct regimes: a short-time intrinsic regime, where $I_c$ scales linearly with the inverse of the pulse length, and a long-time thermally assisted regime where $I_c$ varies weakly. Both regimes are consistent with magnetization reversal proceeding by nucleation and fast propagation of domains. We find that $I_c$ is a factor 3-4 smaller compared to a single domain model and that the incubation time is negligibly small, which is a hallmark feature of spin-orbit torques.
Published: 2014

39. (Invited) Non Volatile Resistive and Magnetic Memories: Materials, Integration Challenges and Opportunities

Author: Marie-Claire Cyrille, Etienne Nowak, Luc Tillie, Gabriel Molas, Gabriele Navarro, Véronique Sousa, Niccolo Castellani, Elisa Vianello, Nathalie Lamard, Youssouf Guerfi, Juergen Langer, Berthold Ocker, Olivier Boulle, Gilles Gaudin, Kevin Garello, Pietro Gambardella, and Luca Perniola
Subjects: Hardware_MEMORYSTRUCTURES
Abstract: Demand for on chip memories has increased due to the need for more data storage and the increasing gap between processor and off chip memory speed. One of the solutions proposed to improve power consumption and to fill the memory gap is to introduce non volatility at different levels of the memory hierarchy (storage class, main memory, cache memory). Several disruptive technologies have been proposed in the last decades for non-volatile memory (NVM) applications. The more investigated ones are Phase-Change Memories (PCM), Conducting-Bridge RAM (CBRAM), Oxide-based Resistive RAM (OxRAM), and Perpendicular Spin Transfer Torque Magnetic Memories (pSTTMRAM). Intensive studies and demonstrations have being carried out in order to develop and improve those emerging memory concepts. Some memory stacks have shown promising results in term of high speed, good endurance or retention but not necessarily all of the above. A survey of published results [1] as well as internal studies carried out at LETI [2, 3] using a memory test vehicle developed to evaluate various memory concepts using the same 130nm CMOS logic have led us to infirm that the universal memory ie an optimized memory stack that fits all requests of memory hierarchy does not exist. However, because requirements for cache memories (ie high speed, endurance, but low data retention) are completely different from requirements for embedded memories (ie high temperature or long data retention), different technology or optimized memory stacks can be targeted to fulfill specific applications. It will be shown that despite very different physical concepts, universal signatures can be extracted unifying the characteristics of different technologies and thus drawing conclusions on their behaviors and tradeoffs (such as programming window vs endurance, programming window vs data retention, and endurance vs data retention). This is illustrated in Fig 1 where the relation between the programming window and the endurance capabilities of the different technologies is presented. It is shown that high programming window is typically associated to poor endurance capabilities, (as shown by some classes of chalco-based CBRAM or non-polar OxRAM). For these technologies the overall filament is believed to participate to the creation and the dissolution events. On the contrary, displacing very few atoms/ions, or spins, during the write or erase event allows to guarantee a long-lasting endurance (examples are certain class of polar OxRAM and STT MRAMs). Data also show that a universal tradeoff exists between the endurance and data retention itself. The better the performances in endurance, the lower the data retention capabilities at high temperature. Write latency speed will be discussed and ultra fast ( The characteristics and performances of the different emerging will be presented (materials, integration, speed, endurance, consumption and scalability) in regards of the needed specifications required for potential applications. [1] ] H.-S. P. Wong, C. Ahn, J. Cao, et al., “Stanford Memory Trends,” https://nano.stanford.edu/stanford-memory-trends, accessed Nov 11, 2015 [2] C. Nail; G. Molas; P. Blaise et al “ Understanding RRAM endurance, retention and window margin trade-off using experimental results and simulations”: IEDM 2016 Pages: 4.5.1 - 4.5.4, DOI: 10.1109/IEDM.2016.7838346 [3] V. Sousa, G. Navarro, N. Castellani et al., “Operation Fundamentals in 12Mb Phase Change Memory Based on Innovative Ge-rich GST Materials Featuring High Reliability Performance”, VLSI Tech. Symp., pp.98-99, 2015 Figure 1
Published: 2017

40. Spin-orbit torques in ferromagnetic heterostructures: fundamentals and applications (presentation video)

Author: Gilles Gaudin, Pietro Gambardella, Stefan Blügel, Frank Freimuth, Can Onur Avci, Mihai Miron, Kevin Garello, Yuriy Mokrousov, and Olivier Boulle
Subjects: Physics, Condensed matter physics, Ferromagnetism, Spin polarization, Magnetism, Spin Hall effect, Spin-transfer torque, Nanomagnet, Spin-½, Magnetic field
Abstract: Current-induced spin torques are of great interest to manipulate the orientation of nanomagnets without applying external magnetic fields. They find direct application in non-volatile data storage and logic devices. Recent demonstrations of perpendicular magnetization switching induced by in-plane current injection in ferromagnetic heterostructures have drawn attention to a class of spin torques based on orbital-to-spin momentum transfer (SOTs), which is alternative to pure spin transfer torque (STT) between non collinear magnetic layers and amenable to more diversified device functions. We will present advance made to build first perpendicular SOT-MRAM devices and to describe the symmetry and amplitudes of SOTs, revealing unexpected physics.
Published: 2014

41. Chirality-Induced Asymmetric Magnetic Nucleation inPt/Co/AlOxUltrathin Microstructures

Author: Ioan Mihai Miron, Gilles Gaudin, Stanislas Rohart, Stefania Pizzini, Jan Vogel, E. Jué, C. K. Safeer, Stéphane Auffret, André Thiaville, Olivier Boulle, and Liliana D. Buda-Prejbeanu
Subjects: Magnetization, Materials science, Field (physics), Condensed matter physics, Magnetic domain, Nucleation, General Physics and Astronomy, Chirality (chemistry), Microstructure, Anisotropy, Magnetic field
Abstract: The nucleation of reversed magnetic domains in Pt/Co/AlO(x) microstructures with perpendicular anisotropy was studied experimentally in the presence of an in-plane magnetic field. For large enough in-plane field, nucleation was observed preferentially at an edge of the sample normal to this field. The position at which nucleation takes place was observed to depend in a chiral way on the initial magnetization and applied field directions. A quantitative explanation of these results is proposed, based on the existence of a sizable Dzyaloshinskii-Moriya interaction in this sample. Another consequence of this interaction is that the energy of domain walls can become negative for in-plane fields smaller than the effective anisotropy field.
Published: 2014

42. Current induced domain wall dynamics in the presence of spin orbit torques

Author: Liliana D. Buda-Prejbeanu, Emilie Jué, Gilles Gaudin, Ioan Mihai Miron, Olivier Boulle, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
Subjects: Physics, Coupling, Condensed Matter - Materials Science, Angular momentum, Condensed Matter - Mesoscale and Nanoscale Physics, Field (physics), Condensed matter physics, Dynamics (mechanics), Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, General Physics and Astronomy, Domain wall (magnetism), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Orbit (dynamics), [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Micromagnetics, ComputingMilieux_MISCELLANEOUS, Spin-½
Abstract: Current induced domain wall (DW) motion in perpendicularly magnetized nanostripes in the presence of spin orbit torques is studied. We show using micromagnetic simulations that the direction of the current induced DW motion and the associated DW velocity depend on the relative values of the field like torque (FLT) and the Slonczewski like torques (SLT). The results are well explained by a collective coordinate model which is used to draw a phase diagram of the DW dynamics as a function of the FLT and the SLT. We show that a large increase in the DW velocity can be reached by a proper tuning of both torques., Comment: 9 pages, 3 figures
Published: 2014

43. Spin-orbit torque magnetization switching of a three-terminal perpendicular magnetic tunnel junction

Author: Juergen Langer, Pietro Gambardella, Kevin Garello, Olivier Boulle, Marc Drouard, M. Cubukcu, Ioan Mihai Miron, Berthold Ocker, Can Onur Avci, Gilles Gaudin, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Department of Materials [ETH Zürich] (D-MATL), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), and Singulus technology AG
Subjects: Condensed Matter - Materials Science, Materials science, Physics and Astronomy (miscellaneous), Condensed matter physics, Magnetoresistance, Condensed Matter - Mesoscale and Nanoscale Physics, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 3. Good health, Magnetic field, Magnetization, Tunnel magnetoresistance, Stack (abstract data type), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Perpendicular, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Torque, Quantum tunnelling, ComputingMilieux_MISCELLANEOUS
Abstract: We report on the current-induced magnetization switching of a three-terminal perpendicular magnetic tunnel junction by spin-orbit torque and the read-out using the tunnelling magnetoresistance (TMR) effect. The device is composed of a perpendicular Ta/FeCoB/MgO/FeCoB stack on top of a Ta current line. The magnetization of the bottom FeCoB layer can be switched reproducibly by the injection of current pulses with density $5\times10^{11}$ A/m$^2$ in the Ta layer in the presence of an in-plane bias magnetic field, leading to the full-scale change of the TMR signal. Our work demonstrates the proof of concept of a perpendicular spin-orbit torque magnetic memory cell., 17 pages, 5 figures
Published: 2014

44. Fieldlike and antidamping spin-orbit torques in as-grown and annealed Ta/CoFeB/MgO layers

Author: Belén Ballesteros, Pietro Gambardella, Aitor Mugarza, Kevin Garello, Can Onur Avci, Eric Pellegrin, Ioan Mihai Miron, Stéphane Auffret, Olivier Boulle, Alessandro Barla, Abhijit Ghosh, Sylvie Godey, Gilles Gaudin, Corneliu Nistor, Manuel Valvidares, European Commission, Competence Centre for Materials Science and Technology (Switzerland), Ministerio de Economía y Competitividad (España), European Research Council, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), ICN2 - Institut Catala de Nanociencia i Nanotecnologia (ICN2), Universitat Autònoma de Barcelona (UAB), ALBA Synchrotron light source [Barcelone], SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Department of Materials [ETH Zürich] (D-MATL), and Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)
Subjects: Materials science, Condensed Matter - Mesoscale and Nanoscale Physics, Condensed matter physics, Annealing (metallurgy), FOS: Physical sciences, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Electronic, Optical and Magnetic Materials, Magnetic anisotropy, Transmission electron microscopy, Hall effect, Electrical resistivity and conductivity, 0103 physical sciences, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 010306 general physics, 0210 nano-technology, Anisotropy, Spectroscopy, Adiabatic process, ComputingMilieux_MISCELLANEOUS
Abstract: Under the terms of the Creative Commons Attribution License 3.0 (CC-BY).-- et al., We present a comprehensive study of the current-induced spin-orbit torques in perpendicularly magnetized Ta/CoFeB/MgO layers. The samples were annealed in steps up to 300 °C and characterized using x-ray-absorption spectroscopy, transmission electron microscopy, resistivity, and Hall effect measurements. By performing adiabatic harmonic Hall voltage measurements, we show that the transverse (fieldlike) and longitudinal (antidampinglike) spin-orbit torques are composed of constant and magnetization-dependent contributions, both of which vary strongly with annealing. Such variations correlate with changes of the saturation magnetization and magnetic anisotropy and are assigned to chemical and structural modifications of the layers. The relative variation of the constant and anisotropic torque terms as a function of annealing temperature is opposite for the fieldlike and antidamping torques. Measurements of the switching probability using sub-μs current pulses show that the critical current increases with the magnetic anisotropy of the layers, whereas the switching efficiency, measured as the ratio of magnetic anisotropy energy and pulse energy, decreases. The optimal annealing temperature to achieve maximum magnetic anisotropy, saturation magnetization, and switching efficiency is determined to be between 240 and 270°C., This work was supported by the the European Commission under the Seventh Framework Programme (GA 318144, SPOT), the European Research Council (StG 203239 NOMAD), the Ministerio de Economía y Competitividad (MAT2010-15659), and the Swiss Competence Centre for Materials Science and Technology (CCMX).
Published: 2014
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45. Current-driven differential resistance phase diagram in nanopillars of NiFe/Cu/NiFe

Author: Olivier Boulle, Albert Fert, M.M. Sanchez, Luis Gustavo Pereira, Frédéric Petroff, and Vicent Cros
Subjects: Magnetization, Materials science, Condensed matter physics, Magnetoresistance, Electrical resistivity and conductivity, Electrical and Electronic Engineering, Thin film, Electric current, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Magnetic field, Phase diagram, Nanopillar
Abstract: In 1996, Slonczewski [J. Magn. Magn. Mater. 159 (1996) 1] and Berger [Phys. Rev. B 54 (1996) 9353] predicted that the magnetization of a thin film can be reversed by spin transfer from a spin-polarized current injected into the film. This effect can be experimentally observed by magnetoresistive measurements. In this work we present a current-driven differential resistance phase diagram for nanopillars of NiFe/Cu/NiFe prepared by e-beam lithography, with lateral dimensions 50 nm × 125 nm . This diagram is obtained by measuring the resistance versus current at constant applied field. We estimated several distinguishable magnetic states as function of both current and magnetic field. Switchings, valleys and peaks can be observed in d V / d I experiments. This behavior is related to the change of the magnetic states induced by a spin-polarized current.
Published: 2006

46. Domain wall tilting in the presence of the Dzyaloshinskii-Moriya interaction in out-of-plane magnetized magnetic nanotracks

Author: Stefania Pizzini, Emilie Jué, Gilles Gaudin, Stanislas Rohart, Jan Vogel, Liliana D. Buda-Prejbeanu, André Thiaville, Olivier Boulle, Ioan Mihai Miron, SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de Physique des Solides (LPS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Micro et NanoMagnétisme (MNM), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Micro et NanoMagnétisme (NEEL - MNM), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Condensed Matter - Materials Science, Condensed matter physics, media_common.quotation_subject, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, General Physics and Astronomy, 02 engineering and technology, 021001 nanoscience & nanotechnology, Magnetostatics, 01 natural sciences, Asymmetry, Magnetic field, Out of plane, Magnetic anisotropy, symbols.namesake, Transverse plane, 0103 physical sciences, Perpendicular, symbols, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 010306 general physics, 0210 nano-technology, Lagrangian, media_common
Abstract: We show that the Dzyaloshinskii-Moriya interaction (DMI) can lead to a tilting of the domain wall (DW) surface in perpendicularly magnetized magnetic nanotracks when DW dynamics is driven by an easy axis magnetic field or a spin polarized current. The DW tilting affects the DW dynamics for large DMI and the tilting relaxation time can be very large as it scales with the square of the track width. The results are well explained by an analytical model based on a Lagrangian approach where the DMI and the DW tilting are included. We propose a simple way to estimate the DMI in a magnetic multilayers by measuring the dependence of the DW tilt angle on a transverse static magnetic field. Our results shed light on the current induced DW tilting observed recently in Co/Ni multilayers with inversion asymmetry, and further support the presence of DMI in these systems., 12 pages, 3 figures, 1 Supplementary Materials
Published: 2013

47. Electric-field control of domain wall nucleation and pinning in a metallic ferromagnet

Author: Stefania Pizzini, Gilles Gaudin, Dominique Givord, Ioan Mihai Miron, Stéphane Auffret, Jan Vogel, Anne Bernand-Mantel, Olivier Boulle, Liza Herrera-Diez, Laurent Ranno, Micro et NanoMagnétisme (MNM), Institut Néel (NEEL), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Micro et NanoMagnétisme (NEEL - MNM), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)
Subjects: Materials science, Physics and Astronomy (miscellaneous), nucleation, Nucleation, FOS: Physical sciences, 02 engineering and technology, domain wall, anisotropy, 01 natural sciences, Magnetization, Electric field, 0103 physical sciences, Electric-field, metallic ferromagnet, pinning, 010306 general physics, Anisotropy, Condensed Matter - Materials Science, Condensed matter physics, 81.05.Bx, 75.50.Cc, 75.60.Ch, 75.70.Cn, Materials Science (cond-mat.mtrl-sci), 021001 nanoscience & nanotechnology, Magnetic field, Domain wall (magnetism), Ferromagnetism, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Electric current, 0210 nano-technology
Abstract: International audience; The electric (E)-field control of magnetic properties opens the prospects of an alternative to magnetic field or electric current activation to control magnetization. Multilayers with perpendicular magnetic anisotropy have proven to be particularly sensitive to the influence of an E-field due to the interfacial origin of their anisotropy. In these systems, E-field effects have been recently applied to assist magnetization switching and control domain wall (DW) velocity. Here we report on two new applications of the E-field in a similar material: controlling domain wall nucleation and stopping DW propagation at the edge of the electrode.
Published: 2013

48. Ferroelectric control of magnetic domains in ultra-thin cobalt layers

Author: Nava Setter, Z. Huang, Stefania Pizzini, Igor Stolichnov, L. Herrera Diez, Laurent Ranno, Gilles Gaudin, Olivier Boulle, J. Borrel, S. Auffret, Anne Bernand-Mantel, Ceramics Laboratory, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland, Ecole Polytechnique Fédérale de Lausanne (EPFL), Micro et NanoMagnétisme (MNM), Institut Néel (NEEL), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), SPINtronique et TEchnologie des Composants (SPINTEC), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Micro et NanoMagnétisme (NEEL - MNM), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)
Subjects: Materials science, Physics and Astronomy (miscellaneous), Magnetic domain, Condensed matter physics, Nucleation, 02 engineering and technology, Coercivity, 021001 nanoscience & nanotechnology, 01 natural sciences, Ferroelectricity, Hysteresis, Magnetic anisotropy, Condensed Matter::Materials Science, Domain wall (magnetism), 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Single domain, 010306 general physics, 0210 nano-technology
Abstract: Non-volatile ferroelectric control of magnetic domains has been demonstrated in ultra-thin cobalt layers at room temperature. The sensitivity of magnetic anisotropy energy to the electronic structure in a few atomic layers adjacent to the interface allows for ferroelectric control of coercivity and magnetic domain dynamics. These effects have been monitored and quantified using magneto-optical Kerr effect. In particular, the regimes, where the ferroelectric domains enhance/inhibit the magnetic domain nucleation or increase/reduce domain wall velocity, have been explored. Thus, non-destructive and reversible ferroelectric domain writing provides a tool to define the magnetic domain paths, create nucleation sites, or control domain movement. (C) 2013 AIP Publishing LLC.
Published: 2013

49. Symmetry and magnitude of spin-orbit torques in ferromagnetic heterostructures

Author: Yuriy Mokrousov, Stéphane Auffret, Can Onur Avci, Pietro Gambardella, Ioan Mihai Miron, Gilles Gaudin, Kevin Garello, Stefan Blügel, Frank Freimuth, Olivier Boulle, European Commission, Ministerio de Economía y Competitividad (España), European Research Council, Generalitat de Catalunya, Centre National de la Recherche Scientifique (France), and Helmholtz Association
Subjects: Biomedical Engineering, Magnitude (mathematics), FOS: Physical sciences, Bioengineering, 02 engineering and technology, 01 natural sciences, Magnetization, 0103 physical sciences, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Torque, General Materials Science, Electrical and Electronic Engineering, 010306 general physics, Spin (physics), Computer Science::Databases, Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Condensed matter physics, Heterojunction, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, Atomic and Molecular Physics, and Optics, Symmetry (physics), Ferromagnetism, Orbit (dynamics), Condensed Matter::Strongly Correlated Electrons, Astrophysics::Earth and Planetary Astrophysics, 0210 nano-technology
Abstract: arXiv:1301.3573.-- et al., Recent demonstrations of magnetization switching induced by in-plane current injection in heavy metal/ferromagnetic heterostructures have drawn increasing attention to spin torques based on orbital-to-spin momentum transfer. The symmetry, magnitude and origin of spin-orbit torques (SOTs), however, remain a matter of debate. Here we report on the three-dimensional vector measurement of SOTs in AlO x/Co/Pt and MgO/CoFeB/Ta trilayers using harmonic analysis of the anomalous and planar Hall effects. We provide a general scheme to measure the amplitude and direction of SOTs as a function of the magnetization direction. Based on space and time inversion symmetry arguments, we demonstrate that heavy metal/ferromagnetic layers allow for two different SOTs having odd and even behaviour with respect to magnetization reversal. Such torques include strongly anisotropic field-like and spin transfer-like components, which depend on the type of heavy metal layer and annealing treatment. These results call for SOT models that go beyond the spin Hall and Rashba effects investigated thus far., This work was supported by the European Research Council (StG 203239 NOMAD), the European Commission under the Seventh Framework Programme (GA 318144, SPOT), Ministerio de Economía y Competitividad (ERA-Net EUI2008-03884, MAT2010-15659), Agència de Gestió d'Ajuts Universitaris i de Recerca (2009 SGR 695) and the Agence Nationale de la Recherche (ANR-10-BLANC-1011-3 ‘SPINHALL’). F.F. and Y.M. acknowledge funding under the HGF-YIG programme VH-NG-513.
Published: 2013
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50. Current induced domain wall dynamics in the presence of a transverse magnetic field in out-of-plane magnetized materials

Author: M. Miron, Liliana D. Buda-Prejbeanu, Gilles Gaudin, and Olivier Boulle
Subjects: Physics, Condensed Matter - Materials Science, Steady state, Deformation (mechanics), Field (physics), Condensed matter physics, Oersted, General Physics and Astronomy, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Magnetization, Domain wall (magnetism), Domain (ring theory), Micromagnetics
Abstract: An analytical model was developped to describe the current induced DW dynamics of a Bloch DW in the presence of an external transverse magnetic field. The model takes into account the DW deformation and the magnetization tilting in the domain. The model is compared to the results of micromagnetic simulation and an excellent agreement is obtained. In the steady state regime, the model shows that the domain tilting does not change the DW mobility. An external or current induced transverse magnetic field such as the Oersted or Rashba field can prevent the Walker breakdown leading to a higher domain wall velocity., to be published in Journal of Applied Physics
Published: 2012

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