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34 results on '"Bernard Rodmacq"'

1. Exchange stiffness in ultrathin perpendicularly magnetized CoFeB layers determined using the spectroscopy of electrically excited spin waves

Author

Ricardo Sousa, Bernard Dieny, Thibaut Devolder, Bernard Rodmacq, Joo-Von Kim, L. E. Nistor, Institut d'électronique fondamentale (IEF), Université Paris-Sud - Paris 11 (UP11)-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), ANR-11-BS10-0003,NanoSWITI,Nanoscale manipulation of spin waves in itinerant ferromagnets: technologies and fundamentals(2011), and ANR-14-CE26-0012,ULTRASKY,Skyrmions dans les couches magnétiques ultraminces en vue d'une spintronique basse consommation(2014)

Subjects
Materials science, Condensed matter physics, General Physics and Astronomy, Stiffness, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Magnetization, Spin wave, Excited state, 0103 physical sciences, medicine, Perpendicular, medicine.symptom, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, 0210 nano-technology, Spectroscopy, Micromagnetics, ComputingMilieux_MISCELLANEOUS, Nanopillar
Abstract

We measure the frequencies of spin waves in nm-thick perpendicularly magnetized FeCoB systems, and model the frequencies to deduce the exchange stiffness of this material in the ultrathin limit. For this, we embody the layers in magnetic tunnel junctions patterned into circular nanopillars of diameters ranging from 100 to 300 nm, and we use magneto-resistance to determine which rf-current frequencies are efficient in populating the spin wave modes. Micromagnetic calculations indicate that the ultrathin nature of the layer and the large wave vectors used ensure that the spin wave frequencies are predominantly determined by the exchange stiffness, such that the number of modes in a given frequency window can be used to estimate the exchange stiffness. For 1 nm layers, the experimental data are consistent with an exchange stiffness A=20±2 pJ/m, which is slightly lower than its bulk counterpart. The thickness dependence of the exchange stiffness has strong implications for the numerous situations that involve...

Published
2016
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2. Fast current-induced domain-wall motion controlled by the Rashba effect

Author

Thomas Moore, Jan Vogel, Marlio Bonfim, Gilles Gaudin, H. Szambolics, Ioan Mihai Miron, Bernard Rodmacq, Alain Schuhl, Liliana D. Buda-Prejbeanu, Stefania Pizzini, Stéphane Auffret, Centre d'Investigació en Nanociència i Nanotecnologia, ICN-CSIC, 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), INPG, Institut Polytechnique de Grenoble - Grenoble Institute of Technology, 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), Departamento de Engenharia Elétrica, Universidade Federal do Paraná (UFPR), ANR-07-NANO-0034,DYNAWALL,Magnetic domain wall dynamics induced by spin polarised current(2007), and Micro et NanoMagnétisme (NEEL - MNM)

Subjects
Physics, Permalloy, Condensed matter physics, Magnetic domain, Mechanical Engineering, media_common.quotation_subject, Nanowire, 02 engineering and technology, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Asymmetry, Instability, Mechanics of Materials, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0103 physical sciences, Torque, General Materials Science, 010306 general physics, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS, Rashba effect, AND gate, media_common
Abstract

The propagation of magnetic domain walls induced by spin-polarized currents has launched new concepts for memory and logic devices. A wave of studies focusing on permalloy (NiFe) nanowires has found evidence for high domain-wall velocities (100 m s(-1); refs,), but has also exposed the drawbacks of this phenomenon for applications. Often the domain-wall displacements are not reproducible, their depinning from a thermally stable position is difficult and the domain-wall structural instability (Walker breakdown) limits the maximum velocity. Here, we show that the combined action of spin-transfer and spin-orbit torques offers a comprehensive solution to these problems. In an ultrathin Co nanowire, integrated in a trilayer with structural inversion asymmetry (SIA), the high spin-torque efficiency facilitates the depinning and leads to high mobility, while the SIA-mediated Rashba field controlling the domain-wall chirality stabilizes the Bloch domain-wall structure. Thus, the high-mobility regime is extended to higher current densities, allowing domain-wall velocities up to 400 m s(-1).

Published
2011
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3. X-ray analysis of oxygen-induced perpendicular magnetic anisotropy in trilayers

Author

Giancarlo Panaccione, Stefania Pizzini, Stéphane Auffret, Lucien Lombard, Bernard Dieny, Bernard Rodmacq, Jan Vogel, Clarisse Ducruet, Aurelien Manchon, M. Hochstrasser, and Vojtech Uhlir

Subjects
Materials science, Absorption spectroscopy, Condensed matter physics, Annealing (metallurgy), Magnetic circular dichroism, 02 engineering and technology, Dichroism, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Electron spectroscopy, Electronic, Optical and Magnetic Materials, Condensed Matter::Materials Science, Nuclear magnetic resonance, X-ray photoelectron spectroscopy, 0103 physical sciences, 010306 general physics, 0210 nano-technology, Anisotropy, Spectroscopy
Abstract

X-ray spectroscopy measurements have been performed on a series of Pt/Co/AlOx trilayers to investigate the role of Co oxidation in the perpendicular magnetic anisotropy of the Co/AlOx interface. It is observed that high temperature annealing modifies the magnetic properties of the Co layer, inducing an enhancement of the perpendicular magnetic anisotropy. The microscopic structural properties are analyzed via X-ray Absorption Spectroscopy, X-ray Magnetic Circular Dichroism and X-ray Photoelectron Spectroscopy measurements. It is shown that annealing enhances the amount of interfacial oxide, which may be at the origin of a strong perpendicular magnetic anisotropy.

Published
2008
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4. Field Dependence of Spin-Transfer Torque Switching Current in Perpendicular Magnetic Tunnel Junctions

Author

Ricardo Sousa, Bernard Rodmacq, Bernard Dieny, Léa Cuchet, Laurent Vila, Stéphane Auffret, 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, Condensed matter physics, Spin-transfer torque, Field dependence, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Electronic, Optical and Magnetic Materials, Condensed Matter::Materials Science, 0103 physical sciences, Perpendicular, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Torque, Critical current, Electrical and Electronic Engineering, Current (fluid), 010306 general physics, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS, Nanopillar
Abstract

Spin-transfer torque switching has been studied on (Co/Pt)/Ta/CoFeB/MgO/FeCoB/Ta patterned perpendicular magnetic tunnel junctions with nanopillar diameters ranging between 100 and 300 nm. Plotting current-field state diagrams, the critical current density for writing was found to be around 3 MA· cm -2 . The field-current dependence of the state transition boundary is linear, with the slope depending on material parameters. Using different thicknesses of top FeCoB free layers, we were able to estimate the Gilbert damping parameter α .

Published
2014
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5. Size dependence of magnetic switching in perpendicularly magnetized MgO/Co/Pt pillars close to the spin reorientation transition

Author

Wolfgang Kuch, Bernard Rodmacq, W. Stefanowicz, Gilles Gaudin, Jan Vogel, Liliana D. Buda-Prejbeanu, Stefania Pizzini, Stéphane Auffret, Lavinia Elena Nistor, Micro et NanoMagnétisme (NEEL - 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), Institut für Experimentalphysik (FU BERLIN), Freie Universität Berlin, 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), 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
010302 applied physics, Materials science, Physics and Astronomy (miscellaneous), Condensed matter physics, chemistry.chemical_element, 02 engineering and technology, Coercivity, 021001 nanoscience & nanotechnology, 01 natural sciences, Magnetization, chemistry, Remanence, 0103 physical sciences, Perpendicular, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Single domain, 0210 nano-technology, Micromagnetics, Cobalt, Spin-½
Abstract

International audience; We investigated the magnetic switching of MgO/Co/Pt pillars with perpendicular magnetic anisotropy, for lateral pillar sizes from 30 nm to 2 lm and for Co layer thicknesses between 1.8 and 2.6 nm. For large pillars, both the coercivity and the remanent magnetization decrease for increasing Co thickness. For all Co thicknesses, the coercivity strongly increases upon decreasing the pillar size. A comparison with micromagnetic simulations shows that the change in coercivity is determined by size-dependent demagnetizing effects. Our results show that small pillars with perpendicular magnetization and a tunable coercivity can be fabricated from continuous layers with in-plane magnetization.

Published
2014
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6. Influence of a Ta spacer on the magnetic and transport properties of perpendicular magnetic tunnel junctions

Author

Bernard Dieny, Clarisse Ducruet, Léa Cuchet, Bernard Rodmacq, Stéphane Auffret, Ricardo C. Sousa, SPINtronique et TEchnologie des Composants (SPINTEC), 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)-Centre National de la Recherche Scientifique (CNRS), ANR-10-NANO-0013,PATHOS,Matériaux à Anisotropie Perpendiculaire pour cellules Mémoire Magnétiques Non-volatiles Haute-densité(2010), European Project: 246942,EC:FP7:ERC,ERC-2009-AdG,HYMAGINE(2010), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-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)

Subjects
010302 applied physics, [PHYS]Physics [physics], Materials science, Physics and Astronomy (miscellaneous), Condensed matter physics, Tantalum, chemistry.chemical_element, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Magnetization, Magnetic anisotropy, Tunnel magnetoresistance, Condensed Matter::Materials Science, Nuclear magnetic resonance, chemistry, Condensed Matter::Superconductivity, 0103 physical sciences, Electrode, Perpendicular, Coupling (piping), 0210 nano-technology, Layer (electronics)
Abstract

International audience; Ultrathin Ta layers were inserted in the bottom hard (Co/Pt)/Ta/CoFeB/MgO magnetic electrode of perpendicular magnetic tunnel junctions. The magnetization of the top part of this electrode abruptly falls in-plane when the Ta thickness exceeds 0.45 nm. This results from the balance between the various energy terms acting on this layer (exchange-like coupling through Ta, demagnetizing energy, and perpendicular anisotropy at the CoFeB/MgO interface). For small Ta thicknesses, this insertion leads to a strong improvement of the tunnel magnetoresistance, as long as the magnetization of all layers remains perpendicular-to-plane.

Published
2013
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7. Spatially periodic domain wall pinning potentials: Asymmetric pinning and dipolar biasing

Author

Robert Stamps, Raphaël Weil, Vincent Baltz, J.-P. Jamet, Peter J. Metaxas, Stanislas Rohart, J. Ferré, Gilles Gaudin, Pierre-Jean Zermatten, R.L. Novak, Bernard Rodmacq, Alexandra Mougin, The University of Western Australia (UWA), Laboratoire de Physique des Solides (LPS), Université Paris-Sud - Paris 11 (UP11)-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), SUPA School of Physics and Astronomy [Glasgow], and University of Glasgow

Subjects
Physics, Field (physics), Condensed matter physics, Condensed Matter - Mesoscale and Nanoscale Physics, General Physics and Astronomy, FOS: Physical sciences, 02 engineering and technology, Coercivity, 021001 nanoscience & nanotechnology, 01 natural sciences, Magnetic field, Magnetization, Hysteresis, Exchange bias, Domain wall (magnetism), Ferromagnetism, 0103 physical sciences, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, 0210 nano-technology
Abstract

Domain wall propagation has been measured in continuous, weakly disordered, quasi-two-dimensional, Ising-like magnetic layers that are subject to spatially periodic domain wall pinning potentials. The potentials are generated non-destructively using the stray magnetic field of ordered arrays of magnetically hard [Co/Pt]$_m$ nanoplatelets which are patterned above and are physically separated from the continuous magnetic layer. The effect of the periodic pinning potentials on thermally activated domain wall creep dynamics is shown to be equivalent, at first approximation, to that of a uniform, effective retardation field, $H_{ret}$, which acts against the applied field, $H$. We show that $H_{ret}$ depends not only on the array geometry but also on the relative orientation of $H$ and the magnetization of the nanoplatelets. A result of the latter dependence is that wall-mediated hysteresis loops obtained for a set nanoplatelet magnetization exhibit many properties that are normally associated with ferromagnet/antiferromagnet exchange bias systems. These include a switchable bias, coercivity enhancement and domain wall roughness that is dependent on the applied field polarity., Comment: 12 pages, 9 figures

Published
2013
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8. Direct Observation of Massless Domain Wall Dynamics in Nanostripes with Perpendicular Magnetic Anisotropy

Author

Stéphane Auffret, Jan Vogel, Olivier Boulle, Ioan Mihai Miron, Bernard Rodmacq, Fausto Sirotti, Julio C. Cezar, Gilles Gaudin, Nicolas Rougemaille, Stefania Pizzini, Marlio Bonfim, 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), European Synchrotron Radiation Facility (ESRF), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), and Micro et NanoMagnétisme (NEEL - MNM)

Subjects
media_common.quotation_subject, General Physics and Astronomy, FOS: Physical sciences, 02 engineering and technology, Inertia, 01 natural sciences, spin torque, 0103 physical sciences, 010306 general physics, media_common, Physics, Condensed Matter - Materials Science, Condensed matter physics, domain walls, Materials Science (cond-mat.mtrl-sci), Nanosecond, inertia, 021001 nanoscience & nanotechnology, Pulse (physics), 75.70.Ak, 75.60.Jk, 07.85.Qe, 75.50.Bb, Massless particle, Domain wall (magnetism), Amplitude, magnetic nanostripes, Domain (ring theory), [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology, Constant (mathematics)
Abstract

Domain wall motion induced by nanosecond current pulses in nanostripes with perpendicular magnetic anisotropy ($\mathrm{Pt}/\mathrm{Co}/{\mathrm{AlO}}_{x}$) is shown to exhibit negligible inertia. Time-resolved magnetic microscopy during current pulses reveals that the domain walls start moving, with a constant speed, as soon as the current reaches a constant amplitude, and no or little motion takes place after the end of the pulse. The very low ``mass'' of these domain walls is attributed to the combination of their narrow width and high damping parameter $\ensuremath{\alpha}$. Such a small inertia should allow accurate control of domain wall motion by tuning the duration and amplitude of the current pulses.

Published
2012
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9. Expansion and relaxation of magnetic mirror domains in a Pt/Co/Pt/Co/Pt multilayer with antiferromagnetic interlayer coupling

Author

Peter J. Metaxas, J.P. Jamet, Robert Stamps, Vincent Baltz, Jacques Ferré, Bernard Rodmacq, The University of Western Australia (UWA), Laboratoire de Physique des Solides (LPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), SUPA School of Physics and Astronomy [Glasgow], University of Glasgow, 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, Condensed matter physics, Field (physics), Magnetism, Relaxation (NMR), Condensed Matter Physics, 01 natural sciences, Magnetic mirror, Dipole, 0103 physical sciences, Domain (ring theory), Perpendicular, Antiferromagnetism, General Materials Science, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, ComputingMilieux_MISCELLANEOUS
Abstract

We detail measurements of field-driven expansion and zero-field relaxation of magnetic mirror domains in antiferromagnetically coupled perpendicularly magnetized ultrathin Co layers. The zero-field stability of aligned ('mirror') domains in such systems results from non-homogeneous dipolar stray fields which exist in the vicinity of the domain walls. During field-driven domain expansion, we evidence a separation of the domain walls which form the mirror domain boundary. However, the walls realign, thereby reforming a mirror domain, if their final separation is below a critical distance at the end of the field pulse. This critical distance marks the point at which the effective net interaction between the walls changes from attractive to repulsive.

Published
2012
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10. Extended scalability and functionalities of MRAM based on thermally-assisted writing

Author

Stéphane Auffret, C. Portemont, Ricardo Sousa, Bertrand Cambou, S. Bandiera, J.P. Nozieres, J. Herault, Bernard Dieny, Ioan Lucian Prejbeanu, Clarisse Ducruet, Bernard Rodmacq, K. Mackay, Erwan Gapihan, and M. Castro Souza

Subjects
010302 applied physics, Magnetoresistive random-access memory, Hardware_MEMORYSTRUCTURES, Memory hierarchy, business.industry, Computer science, Electrical engineering, 02 engineering and technology, Avionics, 021001 nanoscience & nanotechnology, 01 natural sciences, Microcontroller, Hardware_GENERAL, Embedded system, 0103 physical sciences, Scalability, Node (circuits), 0210 nano-technology, business, Dram, Electronic circuit
Abstract

MRAM are already used in low density applications such as microcontrollers or for spatial/avionics applications where they benefit from their radiation hardness. Thermally assisted writing allows extending the downsize scalability of both FIMS and STT-MRAM below the 20nm node. Within a few years, MRAM can play an important role in the memory hierarchy of electronic circuits. They may be first used as DRAM replacement below the 20nm node and in a second step even closer the logic units (Fig.10).

Published
2011
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11. Origin and control of exchange-bias-like phenomenon in coupled ferromagnetic [Pt/Co]/NiFe bilayers

Author

Vincent Baltz, Bernard Rodmacq, Liliana D. Buda-Prejbeanu, Alberto Bollero, Bernard Dieny, Instituto Madrileno de Estudios Avanzados en Nanociencia (IMDEA), 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, Magnetic domain, Condensed matter physics, Magnetometer, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Magnetic susceptibility, Electronic, Optical and Magnetic Materials, law.invention, Condensed Matter::Materials Science, Exchange bias, Ferromagnetism, law, 0103 physical sciences, Antiferromagnetism, Magnetic force microscope, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, 0210 nano-technology, Anisotropy
Abstract

International audience; Domain formation in a [Pt/Co] multilayer with out-of-plane anisotropy leads to a shift of the hysteresis loop of an adjacent NiFe thin film with in-plane anisotropy in an analogous manner to the exchange-bias phenomenon typically observed in ferromagnetic/antiferromagnetic systems. This paper shows that the loop shift can be gradually tuned through modification of the magnitude of the perpendicular anisotropy of the [Pt/Co]/NiFe system by simply varying the thickness of an underlying Pt buffer layer. Magnetometry, magnetotransport, and magnetic force microscopy experimental measurements were made. It appears that the key parameter which controls the exchange-bias effect in this system is the presence of a vortex core in between magnetic domains in the [Pt/Co] multilayer. The magnitude of the exchange-bias is related to the ability to unpin this vortex core, which is related to the magnitude of the perpendicular anisotropy. Micromagnetic simulations illustrate the magnetic configuration responsible for the exchange-bias phenomenon in this nonstandard exchange-biased type system.

Published
2011
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12. Spin-orbit torques in ultrathin ferromagnetic metal layers

Author

Stéphane Auffret, Ioan Mihai Miron, Jan Vogel, Bernard Rodmacq, Gilles Gaudin, Stefania Pizzini, Pietro Gambardella, Alain Schuhl, 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), Centre d'Investigació en Nanociència i Nanotecnologia, ICN-CSIC, 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), and Micro et NanoMagnétisme (NEEL - MNM)

Subjects
Physics, Magnetic structure, Condensed matter physics, Spintronics, Magnetism, Exchange interaction, 02 engineering and technology, Spin–orbit interaction, 021001 nanoscience & nanotechnology, 01 natural sciences, Magnetic field, Condensed Matter::Materials Science, Ferromagnetism, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 010306 general physics, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS, Rashba effect
Abstract

The spin-orbit interaction constitutes a weak but essential perturbation to the Hamiltonian of magnetic systems. Linking spins with atomic structure, spin-orbit coupling assumes a prominent role in structures of reduced dimensionality, where it defines the internal anisotropy fields. In this paper, we discuss interface-enhanced spinorbit effects that arise in metallic multilayers in the presence of an electric current. We demonstrate that a novel type of spin torque can be induced in ferromagnetic metal films lacking structure inversion symmetry through the Rashba effect. Owing to the combination of spin-orbit and exchange interactions, we show that electrons flowing in the plane of a Co layer with asymmetric Pt and AlOx interfaces produce an effective transverse magnetic field of 1 T per 108 A/cm2 of applied current. This torque does not require a current flowing through noncollinear magnetic structures, opening new perspectives for room temperature applications in spintronics.

Published
2010
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13. Dynamic Binding of Driven Interfaces in Coupled Ultrathin Ferromagnetic Layers

Author

Robert Stamps, Peter J. Metaxas, Jacques Ferré, J.P. Jamet, Vincent Baltz, Paolo Politi, Bernard Rodmacq, The University of Western Australia (UWA), Laboratoire de Physique des Solides (LPS), Université Paris-Sud - Paris 11 (UP11)-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), Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, and Consiglio Nazionale delle Ricerche

Subjects
Condensed Matter - Materials Science, Materials science, Field (physics), Condensed matter physics, Dynamic interface, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, General Physics and Astronomy, Disordered Systems and Neural Networks (cond-mat.dis-nn), 02 engineering and technology, Condensed Matter - Disordered Systems and Neural Networks, 021001 nanoscience & nanotechnology, 16. Peace & justice, 01 natural sciences, Domain (mathematical analysis), PACS numbers: 75.60.Ch, 75.78.Fg, 75.70.Cn, Ferromagnetism, 0103 physical sciences, Bound state, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, 0210 nano-technology, Layer (electronics)
Abstract

We demonstrate experimentally dynamic interface binding in a system consisting of two coupled ferromagnetic layers. While domain walls in each layer have different velocity-field responses, for two broad ranges of the driving field, H, walls in the two layers are bound and move at a common velocity. The bound states have their own velocity-field response and arise when the isolated wall velocities in each layer are close, a condition which always occurs as H->0. Several features of the bound states are reproduced using a one dimensional model, illustrating their general nature., 5 pages, 4 figures, to be published in Physical Review Letters

Published
2010
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14. Bimodal distribution of blocking temperature in exchange-biased ferromagnetic/antiferromagnetic bilayers

Author

A. Zarefy, Bernard Rodmacq, Vincent Baltz, L. Lechevallier, Bernard Dieny, 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), Groupe de physique des matériaux (GPM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU), Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), and Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010302 applied physics, Blocking (linguistics), Materials science, Condensed matter physics, Spins, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Electronic, Optical and Magnetic Materials, Geomagnetic reversal, Distribution (mathematics), Exchange bias, Ferromagnetism, 0103 physical sciences, Antiferromagnetism, Condensed Matter::Strongly Correlated Electrons, Crystallite, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 0210 nano-technology, Computer Science::Operating Systems
Abstract

The blocking temperature $({T}_{\text{B}})$ distribution of various polycrystalline ferromagnetic (F)/antiferromagnetic (AF) bilayers exhibits two distinct peaks. This is ascribed to the existence of two families of magnetic entities determining the temperature dependence of exchange bias. One is formed by the AF grains which undergo thermally activated magnetic reversal. The other is formed by F/AF disordered interfacial spins which exhibit spin-glass-like behavior. The bulk versus interfacial nature of these two families is indicated by the dependence of the ${T}_{\text{B}}$ distribution on the AF thickness.

Published
2010
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15. Current-driven spin torque induced by the Rashba effect in a ferromagnetic metal layer

Author

Stéphane Auffret, Ioan Mihai Miron, Bernard Rodmacq, Alain Schuhl, Jan Vogel, Gilles Gaudin, Pietro Gambardella, Stefania Pizzini, 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), Centre d'Investigació en Nanociència i Nanotecnologia, ICN-CSIC, 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), Micro et NanoMagnétisme (NEEL - MNM), and European Research Council

Subjects
perpendicular magnetic anisotropy, 02 engineering and technology, 01 natural sciences, 7. Clean energy, Magnetization, Condensed Matter::Materials Science, Electric field, 0103 physical sciences, General Materials Science, 010306 general physics, ComputingMilieux_MISCELLANEOUS, Physics, spin-orbit torque, Condensed matter physics, Spin polarization, Spintronics, Mechanical Engineering, Spin-transfer torque, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Ferromagnetic resonance, Magnetic field, Mechanics of Materials, [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], 0210 nano-technology, magnetization reversal, Rashba, Rashba effect
Abstract

5 páginas, 4 figuras.-- et al., Methods to manipulate the magnetization of ferromagnets by means of local electric fields or current-induced spin transfer torque allow the design of integrated spintronic devices with reduced dimensions and energy consumption compared with conventional magnetic field actuation. An alternative way to induce a spin torque using an electric current has been proposed based on intrinsic spin–orbit magnetic fields and recently realized in a strained low-temperature ferromagnetic semiconductor. Here we demonstrate that strong magnetic fields can be induced in ferromagnetic metal films lacking structure inversion symmetry through the Rashba effect. Owing to the combination of spin–orbit and exchange interactions, we show that an electric current flowing in the plane of a Co layer with asymmetric Pt and AlOx interfaces produces an effective transverse magnetic field of 1 T per 108 A cm−2. Besides its fundamental significance, the high efficiency of this process makes it a realistic candidate for room-temperature spintronic applications., This work was supported by the European Research Council (Starting Grant 203239).

Published
2010
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16. Effect of electrical current pulses on domain walls in Pt/Co/Pt nanotracks with out-of-plane anisotropy: Spin transfer torque versus Joule heating

Author

Vincent Baltz, André Thiaville, N. Charpentier, Alexandra Mougin, Bernard Rodmacq, Raphaël Weil, F. Piéchon, M. Cormier, Jacques Ferré, Laboratoire de Physique des Solides (LPS), Université Paris-Sud - Paris 11 (UP11)-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)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Materials science, Condensed matter physics, Magnetic domain, Demagnetizing field, Spin-transfer torque, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Electronic, Optical and Magnetic Materials, Nuclear magnetic resonance, 0103 physical sciences, Current (fluid), [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, 0210 nano-technology, Anisotropy, Joule heating, Current density, Spin-½
Abstract

International audience; The effect of electrical current pulses on magnetic domain walls is studied in a nanometer-scale magnetic track defined in a He +-irradiated Pt/Co0.5 nm/Pt film with out-of-plane anisotropy. Current pulses in a wide range of intensities and durations are shown to result either in track demagnetization, or in polarity-independent domain-wall propagation, due to Joule heating during the current pulse. None of the expected spin transfer effects is shown to occur. To explain this, the spin-dependent current-density distribution in the stack is evaluated, in the frame of an adapted Fuchs-Sondheimer model. The spin-polarized current density in the cobalt layer is shown to be unexpectedly low as compared to the charge current in the whole stack, which causes Joule heating. This is explained by a low electron transmission at Co/Pt interfaces, as is deduced from resistance measurements on a series of samples with different cobalt thicknesses. This leads us to emphasize that the balance between spin and total charge current densities should be carefully considered when addressing spin transfer torque effects.

Published
2010
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17. Structural analysis and magnetic properties of(Pt/Co)3/PttPt/IrMnmultilayers

Author

Rodrigue Lardé, Bernard Rodmacq, L. Lechevallier, J.M. Le Breton, Vincent Baltz, A. Zarefy, H. Chiron, and Bernard Dieny

Subjects
Materials science, 02 engineering and technology, Atom probe, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Electronic, Optical and Magnetic Materials, law.invention, Crystallography, Ferromagnetism, law, 0103 physical sciences, Antiferromagnetism, 010306 general physics, 0210 nano-technology, Anisotropy
Abstract

Structural and magnetic investigations of ${\text{Ta}}_{3\text{ }\text{nm}}/{[{({\text{Pt}}_{2\text{ }\text{nm}}/{\text{Co}}_{0.4\text{ }\text{nm}})}_{3}/{\text{Pt}}_{t\text{Pt}}/{\text{IrMn}}_{7\text{ }\text{nm}}]}_{7}/{\text{Pt}}_{10\text{ }\text{nm}}$ multilayers with ${t}_{\text{Pt}}=0$ and ${t}_{\text{Pt}}=0.4\text{ }\text{nm}$ have been carried out using x-ray reflectometry, tomographic atom probe, and superconducting quantum interference device magnetometry. The structural investigations show that the Co/IrMn interface is more diffuse in the absence of the Pt spacer. The consequences on the magnetic properties are discussed. The exchange-bias field and the anisotropy direction of these two specimens are analyzed in comparison to ${\text{Ta}}_{3\text{ }\text{nm}}/[{({\text{Pt}}_{2\text{ }\text{nm}}/{\text{Co}}_{0.4\text{ }\text{nm}})}_{3}/{\text{Pt}}_{t\text{Pt}}/{\text{IrMn}}_{7\text{ }\text{nm}}]/{\text{Pt}}_{10\text{ }\text{nm}}$ multilayers containing only one ferromagnetic/antiferromagnetic repeat and correlated with the structural investigations.

Published
2009
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18. Investigation of metallic/oxide interfaces in Pt/Co/AlOx trilayers by hard x-ray reflectivity

Author

P. Plaindoux, H. Garad, B. Zawilski, Bernard Dieny, F. Fettar, Stéphane Auffret, Bernard Rodmacq, Luc Ortega, A.Y. Ramos, Surfaces, Interfaces et Nanostructures (SIN), 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), X'Press (X'Press), Matériaux, Rayonnements, Structure (MRS), Automatisation et Caractérisation (AUTOCARAC), 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), Surfaces, Interfaces et Nanostructures (NEEL - SIN), 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), X'Press : diffraction et hautes pressions (NEEL - X'Press), Matériaux, Rayonnements, Structure (NEEL - MRS), and Automatisation & caractérisation (NEEL - AUTOCARAC)

Subjects
Materials science, oxidation, perpendicular magnetic anisotropy, Analytical chemistry, Oxide, chemistry.chemical_element, 02 engineering and technology, 01 natural sciences, Metal, chemistry.chemical_compound, reflectometry X-ray chemical analysis, Hall effect, 0103 physical sciences, Magnetic layered films, Electrical and Electronic Engineering, 010306 general physics, Magnetic structure, Condensed matter physics, 021001 nanoscience & nanotechnology, Electronic, Optical and Magnetic Materials, X-ray reflectivity, Magnetic anisotropy, chemistry, metal-insulator structures, visual_art, visual_art.visual_art_medium, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], X-ray measurements, 0210 nano-technology, Platinum, Cobalt
Abstract

International audience; X-ray reflectivity (XRR) is used to determine the oxidation front at the nanometer scale in sputtered perpendicular semi tunnel junctions, as the form Pt/Co/AlOx, by varying the oxidation time tOx of the capping layer. From XRR simulations, we show that the nature of the stack is gradually defined according to the value of tOx. For low tOx values (

Published
2009
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19. High domain wall velocities induced by current in ultrathin Pt/Co/AlOx wires with perpendicular magnetic anisotropy

Author

Gilles Gaudin, T. A. Moore, Stefania Pizzini, G. Serret, Stéphane Auffret, Alain Schuhl, Bernard Rodmacq, Marlio Bonfim, Ioan Mihai Miron, Jan Vogel, 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 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), Departamento de Engenharia Elétrica, Universidade Federal do Paraná (UFPR), ANR-07-NANO-0034,DYNAWALL,Magnetic domain wall dynamics induced by spin polarised current(2007), 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
Materials science, Physics and Astronomy (miscellaneous), Kerr microscopy, Perpendicular magnetic anisotropy, FOS: Physical sciences, 02 engineering and technology, domain wall, 01 natural sciences, spin torque, Current pulse, perpendicular anisotropy, 0103 physical sciences, ComputingMilieux_MISCELLANEOUS, 010302 applied physics, Condensed matter physics, 021001 nanoscience & nanotechnology, Condensed Matter - Other Condensed Matter, Domain wall (magnetism), Amplitude, Creep, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], PACS : 75.70.Kw, 75.60.Ch, 75.30.Gw, 78.20.Ls, Current (fluid), 0210 nano-technology, Displacement (fluid), Current density, Other Condensed Matter (cond-mat.other)
Abstract

Current-induced domain wall (DW) displacements in an array of ultrathin Pt/Co/AlOx wires with perpendicular magnetic anisotropy have been directly observed by wide field Kerr microscopy. DWs in all wires in the array were driven simultaneously and their displacement on the micrometer-scale was controlled by the current pulse amplitude and duration. At the lower current densities where DW displacements were observed (j less than or equal to 1.5 x 10^12 A/m^2), the DW motion obeys a creep law. At higher current density (j = 1.8 x 10^12 A/m^2), zero-field average DW velocities up to 130 +/- 10 m/s were recorded., Comment: Minor changes to Fig. 1(b) and text, correcting for the fact that domain walls were subsequently found to move counter to the electron flow. References updated

Published
2008
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20. Creep and Flow Regimes of Magnetic Domain-Wall Motion in UltrathinPt/Co/PtFilms with Perpendicular Anisotropy

Author

Bernard Dieny, Jacques Ferré, Bernard Rodmacq, J.P. Jamet, Vincent Baltz, Peter J. Metaxas, M. Cormier, Alexandra Mougin, and Robert Stamps

Subjects
Physics, Condensed matter physics, Magnetic domain, General Physics and Astronomy, 02 engineering and technology, Dissipation, 021001 nanoscience & nanotechnology, 01 natural sciences, Magnetic field, Flow (mathematics), Creep, 0103 physical sciences, Viscous flow, Perpendicular anisotropy, Wall motion, 010306 general physics, 0210 nano-technology
Abstract

We report on magnetic domain-wall velocity measurements in ultrathin $\mathrm{Pt}/\mathrm{Co}(0.5--0.8\text{ }\text{ }\mathrm{nm})/\mathrm{Pt}$ films with perpendicular anisotropy over a large range of applied magnetic fields. The complete velocity-field characteristics are obtained, enabling an examination of the transition between thermally activated creep and viscous flow: motion regimes predicted from general theories for driven elastic interfaces in weakly disordered media. The dissipation limited flow regime is found to be consistent with precessional domain-wall motion, analysis of which yields values for the damping parameter, $\ensuremath{\alpha}$.

Published
2007
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21. Multilevel magnetic nanodot arrays with out of plane anisotropy: the role of intra-dot magnetostatic coupling

Author

Vincent Baltz, J.P. Jamet, Jacques Ferré, Alberto Bollero, Bernard Rodmacq, Bernard Dieny, 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), and Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Coupling, Materials science, Nanostructure, Condensed matter physics, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 01 natural sciences, Electronic, Optical and Magnetic Materials, Condensed Matter::Materials Science, Amplitude, Transition metal, 0103 physical sciences, Nanodot, Single domain, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, 0210 nano-technology, Anisotropy, Instrumentation, Layer (electronics)
Abstract

International audience; Intra-dot inter-layer magnetostatic coupling have been investigated in trilayers which consist of two [Co/Pt] multilayers with out-of-plane anisotropy and different coercivities separated by a thick Pt layer. For single domain nanodots, the strong intra-dot inter-layer magnetostatic interactions manifest as a shift of the soft layer hysteresis loop. The amplitude of this shift decreases when the size of the dots is increased and/or when the temperature is increased. Satisfactory agreement is found between calculations and experimental results. PACS. 75 Magnetic properties and materials-75.70.-i Magnetic properties of thin films, surfaces, and interfaces-75.60.-d Domain effects, magnetization curves, and hysteresis-75.60.Ch Domain walls and domain structure-75.75.+a Magnetic properties of nanostructures

Published
2007
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22. Magnetic domain replication in interacting bilayers with out-of-plane anisotropy: Application toCo∕Ptmultilayers

Author

Vincent Baltz, Bernard Rodmacq, Alain Marty, and Bernard Dieny

Subjects
010302 applied physics, Materials science, Condensed matter physics, Magnetic domain, 02 engineering and technology, Replication (microscopy), Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Coupling (probability), 01 natural sciences, Electronic, Optical and Magnetic Materials, Condensed Matter::Materials Science, Magnetization, Ferromagnetism, Condensed Matter::Superconductivity, 0103 physical sciences, Domain (ring theory), 0210 nano-technology, Anisotropy, Layer (electronics)
Abstract

The effects of domain replication resulting from interlayer magnetostatic coupling have been investigated in trilayers which consist of two $\mathrm{Co}∕\mathrm{Pt}$ multilayers with out-of-plane anisotropy separated by a thick Pt layer. For demagnetized films, the strong correlation between the domain configurations of the two multilayers gives rise to an evolution of the equilibrium domain size with the spacer layer thickness. A good correspondence is found between our numerical calculations and the experimental measurements. These results are an extension of Kaplan's theory of domain size in single ferromagnetic films with out-of-plane magnetization, to the case of interacting ferromagnetic films.

Published
2007
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23. Magnetic behavior of systems composed of coupled ferromagnetic bilayers with distinct anisotropy directions

Author

Bernard Dieny, Liliana D. Buda-Prejbeanu, Vincent Baltz, Jordi Sort, Bernard Rodmacq, Alberto Bollero, 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), and Universitat Autònoma de Barcelona (UAB)

Subjects
010302 applied physics, Materials science, Condensed matter physics, Magnetic domain, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Magnetic hysteresis, 01 natural sciences, Magnetic susceptibility, Electronic, Optical and Magnetic Materials, Magnetic anisotropy, Magnetization, Condensed Matter::Materials Science, Exchange bias, 0103 physical sciences, Single domain, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 0210 nano-technology, Saturation (magnetic)
Abstract

A shift in the hysteresis loop of a $\mathrm{NiFe}$ thin film (with in-plane anisotropy) exchange coupled to a $[\mathrm{Pt}∕\mathrm{Co}]$ multilayer (with out-of-plane anisotropy) is observed after in-plane saturation of the system. The origin of this effect and the related magnetic properties are investigated by means of in-plane and out-of-plane magnetometry techniques, magnetic force microscopy imaging, and micromagnetic simulations. Both the number of $\mathrm{Pt}∕\mathrm{Co}$ repetitions in the multilayer and the $\mathrm{NiFe}$ thickness are found to have an influence on the magnitude of the loop shift and the in-plane and out-of-plane coercivity values of the system. This is correlated with variations in the number and average size of the magnetic domains formed in the $[\mathrm{Pt}∕\mathrm{Co}]$ multilayer which, as revealed by micromagnetic simulations, pin the $\mathrm{NiFe}$ magnetization via formation of closure domains with a preferential orientation at the interface between the $[\mathrm{Pt}∕\mathrm{Co}]$ multilayer and the $\mathrm{NiFe}$.

Published
2006
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24. Macroscopic probing of domain configurations in interacting bilayers with perpendicular magnetic anisotropy

Author

Bernard Dieny, Vincent Baltz, Bernard Rodmacq, 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, Condensed matter physics, Field (physics), Order (ring theory), Condensed Matter Physics, 01 natural sciences, Electronic, Optical and Magnetic Materials, Hysteresis, Magnetization, Amplitude, 0103 physical sciences, Domain (ring theory), Perpendicular, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, Layer (electronics)
Abstract

International audience; Magnetostatic interactions in perpendicularly magnetized Co/ Pt bilayers lead to the formation of mirror domains in both soft and hard layers. We show that it is possible to take advantage of domain replication in order to probe the microscopic domain configuration of the hard layer through macroscopic hysteresis minor loop measurements on the soft layer. The minor curves consist of two loops, which magnetization amplitudes and field shifts can be quantitatively related to the domains sizes, shapes, and up/down relative proportion in the hard layer.

Published
2006
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25. Thermal activation effects on the exchange bias in ferromagnetic-antiferromagnetic nanostructures

Author

Bernard Dieny, Jordi Sort, Bernard Rodmacq, S. Landis, Vincent Baltz, 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), and Direction de Recherche Technologique (CEA) (DRT (CEA))

Subjects
Nanostructure, Materials science, Magnetic domain, Condensed matter physics, 02 engineering and technology, Activation energy, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Magnetic hysteresis, 01 natural sciences, Electronic, Optical and Magnetic Materials, 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, Phase diagram
Abstract

The hysteresis loop shift ${H}_{E}$ of sub-$100\text{\ensuremath{-}}\mathrm{nm}$ ferromagnetic- (FM-) antiferromagnetic (AFM) nanostructures is found to be strongly influenced by thermal activation effects. These effects, which tend to reduce ${H}_{E}$, are more pronounced in the nanostructures than in continuous films with the same composition, particularly for thin AFM layers. In addition, the reduced dimensions of the nanostructures also impose spatial constraints to the AFM domain size, particularly for thick AFM layers. This favors an enhancement of ${H}_{E}$. Due to the interplay between these two competing effects, the loop shift in the dots can be either larger or smaller than in the continuous films with the same composition, depending on both the AFM thickness and temperature. A temperature-AFM thickness phase diagram, separating the conditions resulting in larger or smaller ${H}_{E}$ in the nanostructures with respect to continuous film is derived.

Published
2005
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26. Multilevel magnetic media in continuous and patterned films with out-of-plane magnetization

Author

Bernard Dieny, Bernard Rodmacq, S. Landis, Vincent Baltz, 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), and Direction de Recherche Technologique (CEA) (DRT (CEA))

Subjects
010302 applied physics, Materials science, Magnetic domain, Condensed matter physics, 02 engineering and technology, Coercivity, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Electronic, Optical and Magnetic Materials, Condensed Matter::Materials Science, Magnetization, Magnetic anisotropy, Ferromagnetism, 0103 physical sciences, Patterned media, Nanodot, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 0210 nano-technology, Anisotropy, ComputingMilieux_MISCELLANEOUS
Abstract

In conventional high-density magnetic media, information is stored in the form of magnetic domains oriented in two possible remanent states along an easy axis of anisotropy. In order to further increase the areal density keeping the same bit size, multilevel magnetic media consisting of N decoupled ferromagnetic storage layers ( N ⩾2) with different coercivities can be used. In such a case, the recording media exhibit up to 2 N stable remanent states. In this study, decoupled (Co/Pt) multilayers systems with perpendicular anisotropy have been sputtered on continuous silicon substrates and arrays of pre-patterned silicon nanodots in order to achieve magnetic continuous and patterned multilevel media. These media were characterized from a magnetic point of view.

Published
2005
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27. Tailoring Size Effects on the Exchange Bias in Ferromagnetic-Antiferromagnetic<100 nmNanostructures

Author

S. Landis, Bernard Dieny, Bernard Rodmacq, Jordi Sort, and Vincent Baltz

Subjects
Permalloy, Materials science, Nanostructure, Condensed matter physics, General Physics and Astronomy, Nanotechnology, 02 engineering and technology, Coercivity, 021001 nanoscience & nanotechnology, Magnetic hysteresis, 01 natural sciences, Quantitative Biology::Subcellular Processes, Condensed Matter::Materials Science, Exchange bias, Ferromagnetism, 0103 physical sciences, Antiferromagnetism, Condensed Matter::Strongly Correlated Electrons, 010306 general physics, 0210 nano-technology, Electron-beam lithography
Abstract

The hysteresis loop shift in sub-100 nm ferromagnetic- (FM-)antiferromagnetic (AFM) nanostructures can be either enhanced or reduced with respect to continuous films with the same composition, with varying the AFM layer thickness. An enhancement of the coercivity and a reduction of the blocking temperature are also observed. These effects are mainly ascribed to the physical limitations that the dot sizes impose on the AFM domain size and the concomitant weakening of the pinning strength exerted by the AFM during magnetization reversal of the FM.

Published
2005
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28. Tailoring perpendicular exchange bias in [Pt/Co]-IrMn multilayers

Author

Flávio Garcia, Vincent Baltz, Bernard Rodmacq, Jordi Sort, Bernard Dieny, 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, Materials science, Condensed matter physics, 02 engineering and technology, Coercivity, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Magnetic hysteresis, 01 natural sciences, Electronic, Optical and Magnetic Materials, Orientation (vector space), Condensed Matter::Materials Science, Magnetization, Magnetic anisotropy, Exchange bias, Ferromagnetism, 0103 physical sciences, Antiferromagnetism, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 0210 nano-technology
Abstract

In [Pt/Co] multilayers (ML) exchange coupled to IrMn, the magnitudes of the exchange bias field ${H}_{E}$ and coercivity ${H}_{C}$ measured along the perpendicular to film direction, can be tailored by (i) varying the thickness of the Co layers $({t}_{\mathrm{Co}})$ inside the ML and/or (ii) inserting a Pt spacer between the ML and the antiferromagnetic (AFM) layer. An unusual peak in the ferromagnetic (FM) thickness dependence of exchange bias properties is observed. This is ascribed to a reduction of the perpendicular effective magnetic anisotropy for either very small or too large values of ${t}_{\mathrm{Co}}$. Moreover, for low values of ${t}_{\mathrm{Co}}$, the insertion of an ultrathin Pt spacer between the [Pt/Co] ML and the IrMn brings about a significant increase of ${H}_{E}$ and ${H}_{C}$. However, such an effect is not observed for thicker Co layers. This behavior is explained by the two-fold role of the Pt spacer, i.e., it strengthens the perpendicular orientation of the Co magnetization in the ML but it also tends to reduce exchange bias due to the short-range character of the FM-AFM interactions.

Published
2005
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29. Magnetic relaxation of exchange biased (Pt/Co) multilayers studied by time-resolved Kerr microscopy

Author

Marlio Bonfim, Fabien Romanens, Julio Camarero, Bernard Dieny, Stefania Pizzini, Flávio Garcia, Jan Vogel, Yan Pennec, Bernard Rodmacq, Fabiano Yokaichiya, Jordi Sort, Laboratoire Louis Néel (LLN), Centre National de la Recherche Scientifique (CNRS), Departamento de Engenharia Elétrica, Universidade Federal do Paraná (UFPR), Departamento de Fisica de la Materia Condensada [Madrid] (FMC), Facultad de Ciencas [Madrid], Universidad Autonoma de Madrid (UAM)-Universidad Autonoma de Madrid (UAM), 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), and Universidad Autónoma de Madrid (UAM)-Universidad Autónoma de Madrid (UAM)

Subjects
Kerr effect, Materials science, Magnetic domain, Kerr microscopy, Nucleation, FOS: Physical sciences, 02 engineering and technology, 01 natural sciences, Magnetization, perpendicular anisotropy, Transition metal, 0103 physical sciences, 75.60.Jk, 75.60.Ch, 75.60.Lr, 75.70.Cn, 010306 general physics, Condensed matter physics, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Condensed Matter - Other Condensed Matter, Exchange bias, exchange bias, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0210 nano-technology, magnetization reversal, Antiparallel (electronics), Other Condensed Matter (cond-mat.other)
Abstract

Magnetization relaxation of exchange biased (Pt/Co)5/Pt/IrMn multilayers with perpendicular anisotropy was investigated by time-resolved Kerr microscopy. Magnetization reversal occurs by nucleation and domain wall propagation for both descending and ascending applied fields, but a much larger nucleation density is observed for the descending branch, where the field is applied antiparallel to the exchange bias field direction. These results can be explained by taking into account the presence of local inhomogeneities of the exchange bias field., To appear in Physical Review B (October 2005)

Published
2005
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30. Fabrication and Characterization of Magnetic Media Deposited on Top or Side Edges of Silicon Dots

Author

Vincent Baltz, Pascale Bayle-Guillemaud, Bernard Rodmacq, Bernard Dieny, S. Landis, 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)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), 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)), Laboratoire d'Etude des Matériaux par Microscopie Avancée (LEMMA ), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-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 [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), 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 [2016-2019] (UGA [2016-2019])

Subjects
010302 applied physics, Fabrication, Materials science, Silicon, General Engineering, General Physics and Astronomy, chemistry.chemical_element, Nanotechnology, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Condensed Matter::Materials Science, chemistry, Transmission electron microscopy, Magnet, 0103 physical sciences, Patterned media, Reactive-ion etching, Magnetic force microscope, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 0210 nano-technology, Electron-beam lithography, ComputingMilieux_MISCELLANEOUS
Abstract

Arrays of lines and dots were patterned on silicon substrates by electron beam lithography and reactive ion etching. Co/Pt multilayers were sputter-deposited on these patterned substrates to realize perpendicular patterned media for ultra high-density magnetic recording. Magnetic material thus covers the top of the lines and dots, the bottom of the grooves between nanostructures, and to a lesser extent, the sidewalls. Magnetic properties were characterized by both macroscopic and magnetic force microscopy experiments. From the results obtained from high-resolution transmission electron microscopy (TEM) experiments, we propose a new approach for realizing patterned magnetic media using the side edges instead of the top of the dots.

Published
2004
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31. Competition between CoOx and CoPt phases in Pt/Co/AlOx semi tunnel junctions

Author

F. Fettar, Bernard Dieny, Olivier Proux, Aline Y. Ramos, Yves Joly, Bernard Rodmacq, Houmed Garad, Stéphane Auffret, Luc Ortega, Alexei Erko, Surfaces, Interfaces et Nanostructures (NEEL - SIN), 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), Laboratoire de Physique des Solides (LPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Matériaux, Rayonnements, Structure (NEEL - MRS), 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), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Surfaces, Interfaces et Nanostructures (SIN), 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), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Matériaux, Rayonnements, Structure (MRS), SIN - Surfaces, Interfaces et Nanostructures, Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), MRS - Matériaux, Rayonnements, Structure, Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), and Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)

Subjects
Materials science, oxidation, Annealing (metallurgy), cobalt alloys, Alloy, General Physics and Astronomy, chemistry.chemical_element, platinum alloys, 02 engineering and technology, Surface finish, engineering.material, 01 natural sciences, X-ray absorption, Bulk samples, 0103 physical sciences, nanostructured materials, platinum, nanomagnetics, magnetic multilayers, 010306 general physics, sputter deposition, Metallurgy, Sputter deposition, 021001 nanoscience & nanotechnology, X-ray reflection, cobalt, alumina, Nanolithography, chemistry, Chemical engineering, PACS 75.75.Cd, 75.50.Tt, 75.70.Cn, 78.70.Dm, 81.15.Cd, 81.40.Gh, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], engineering, nanofabrication, annealing, 0210 nano-technology, Platinum, Cobalt
Abstract

10 pages; International audience; We report on the evolution of the structure and composition of a Pt(3 nm)/Co(0.6 nm)/AlOx(2 nm) trilayer sputtered on Si/SiO2 under oxidation and annealing processes by combined x-ray reflectivity and x-ray absorption studies. We describe the progressive and inhomogeneous oxidation of the layers by increasing the oxidation time. Before annealing, the layers have lower density than bulk samples and noticeable roughness. After thermal annealing, a significant improvement of the quality of the alumina layer goes along with the formation of a CoPt alloy that reduces the number of Co-O bonds. These structural outcomes clarify the evolution of the magnetic and transport properties reported at room temperature in these samples.

Published
2013
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32. Influence of Co layer thickness on the structural and magnetic properties of multilayers

Author

Bernard Dieny, Bernard Rodmacq, A. Zarefy, H. Chiron, J-M Le Breton, L. Lechevallier, Vincent Baltz, Rodrigue Lardé, Groupe de physique des matériaux (GPM), Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-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), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), and Normandie Université (NU)

Subjects
Acoustics and Ultrasonics, Magnetism, Analytical chemistry, 02 engineering and technology, Atom probe, 01 natural sciences, law.invention, Magnetization, law, 0103 physical sciences, Antiferromagnetism, 75.30.Gw, magnetic multilayers, [PHYS]Physics [physics], 010302 applied physics, tomographic atom probe PACS numbers: 68.43.Tj, 75.70.Cn, Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Magnetic susceptibility, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Hysteresis, Exchange bias, Ferromagnetism, Condensed Matter::Strongly Correlated Electrons, 0210 nano-technology
Abstract

The correlated effects of the insertion of a Pt spacer between ferromagnetic and antiferromagnetic layers and of the variation of the Co layers' thickness on the structural and magnetic properties of multilayers have been studied. Samples with n = 1 and 7, t Co = 0.4 and 0.6 nm, t Pt = 0 and 0.4 nm have been investigated by tomographic atom probe and superconducting quantum interference device magnetometry. For spacer-free samples (t Pt = 0), the structural investigation shows that when t Co = 0.4 nm, Mn and Ir atoms diffuse deeply into the (Pt/Co)3 multilayers. In contrast for t Co = 0.6 nm, the Mn and Ir diffusion is much reduced. Because Pt acts as a barrier against the Mn and Ir diffusion, this difference is less pronounced in samples with Pt insertion. The hysteresis loops shapes, the exchange bias fields and the saturation magnetization values were correlated with the structural properties of these samples and discussed, taking into account the susceptibility, exchange stiffness and perpendicular magnetic anisotropy.

Published
2010
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33. Spin injection in silicon at zero magnetic field

Author

Matthieu Jamet, Vincent Calvo, Bernard Rodmacq, Yves Samson, Lavinia Elena Nistor, Stéphane Auffret, P. Warin, Jean-Michel Hartmann, L. Grenet, Pierre Noé, Service de Physique des Matériaux et Microstructures (SP2M - UMR 9002), Institut Nanosciences et Cryogénie (INAC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), 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)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), 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)), and 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))

Subjects
010302 applied physics, Condensed Matter - Materials Science, Materials science, Physics and Astronomy (miscellaneous), Condensed matter physics, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Polarization (waves), 01 natural sciences, Magnetic field, Magnetization, Magnetic anisotropy, Ferromagnetism, Remanence, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 010306 general physics, Anisotropy, Circular polarization
Abstract

In this letter, we show efficient electrical spin injection into a SiGe based \textit{p-i-n} light emitting diode from the remanent state of a perpendicularly magnetized ferromagnetic contact. Electron spin injection is carried out through an alumina tunnel barrier from a Co/Pt thin film exhibiting a strong out-of-plane anisotropy. The electrons spin polarization is then analysed through the circular polarization of emitted light. All the light polarization measurements are performed without an external applied magnetic field \textit{i.e.} in remanent magnetic states. The light polarization as a function of the magnetic field closely traces the out-of-plane magnetization of the Co/Pt injector. We could achieve a circular polarization degree of the emitted light of 3 % at 5 K. Moreover this light polarization remains almost constant at least up to 200 K., Comment: accepted in APL

Published
2009
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34. Magnetic domain structure and dynamics in interacting ferromagnetic stacks with perpendicular anisotropy

Author

Vincent Baltz, Nicolas Vernier, Alexandra Mougin, Bernard Rodmacq, Bernard Dieny, S. Wiebel, J.-P. Jamet, Jacques Ferré, Laboratoire de Physique des Solides (LPS), Université Paris-Sud - Paris 11 (UP11)-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)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Condensed Matter - Materials Science, Materials science, Magnetic domain, Field (physics), 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, Magnetic field, Magnetization, Domain wall (magnetism), Ferromagnetism, 0103 physical sciences, Domain (ring theory), Time domain, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, 0210 nano-technology
Abstract

The time and field dependence of the magnetic domain structure at magnetization reversal were investigated by Kerr microscopy in interacting ferromagnetic Co/Pt multilayers with perpendicular anisotropy. Large local inhomogeneous magnetostatic fields favor mirroring domain structures and domain decoration by rings of opposite magnetization. The long range nature of these magnetostatic interactions gives rise to ultra-slow dynamics even in zero applied field, i.e. it affects the long time domain stability. Due to this additionnal interaction field, the magnetization reversal under short magnetic field pulses differs markedly from the well-known slow dynamic behavior. Namely, in high field, the magnetization of the coupled harder layer has been observed to reverse more rapidly by domain wall motion than the softer layer alone., 42 pages including 17 figures. submitted to JAP

Published
2006
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