24 results on '"Sylvain Eimer"'
Search Results
2. Perpendicular magnetic anisotropy based spintronics devices in Pt/Co irradiatedand Pt/Co/RuO2/Pt stacks under different substrates
- Author
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Sylvain, Eimer, primary, houyi, Cheng, primary, pierre, Vallobra, primary, boyu, Zhang, primary, and weisheng, Zhao, primary
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- 2023
- Full Text
- View/download PDF
3. Mo-based perpendicularly magnetized thin films with low damping for fast and low-power consumption magnetic memory
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Houyi Cheng, Boyu Zhang, Yong Xu, Shiyang Lu, Yuxuan Yao, Rui Xiao, Kaihua Cao, Yongshan Liu, Zilu Wang, Renyou Xu, Danrong Xiong, Yan Wang, Helin Ma, Sylvain Eimer, Chao Zhao, and Weisheng Zhao
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General Physics and Astronomy - Published
- 2022
4. Ultrafast single-pulse switching of Tb-dominant CoTb alloy
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Yongshan Liu, Houyi Cheng, Pierre Vallobra, Huiwen Wang, Sylvain Eimer, Xiaoqiang Zhang, Gregory Malinowski, Michel Hehn, Yong Xu, Stephane Mangin, and Weisheng Zhao
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Physics and Astronomy (miscellaneous) - Abstract
Single-pulse magnetization switching by femtosecond laser pulses is the fastest way to manipulate magnetization. To date, among rare-earth transition metal alloys, single-pulse switching is limited to Gd-based structures. Here, we demonstrate ultrafast single-pulse switching of Tb-dominant CoTb alloys within several tens of picoseconds. Our further analysis shows that the ultrafast magnetization reversal is linked to ultrafast heating of laser pulses and an external field.
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- 2023
5. Separation of emission mechanisms in spintronic terahertz emitters
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Weisheng Zhao, Xiaojun Wu, Xiaoqiang Zhang, Tianxiao Nie, Pierre Vallobra, Yong Xu, Yongshan Liu, Houyi Cheng, and Sylvain Eimer
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Materials science ,Condensed matter physics ,Spintronics ,Terahertz radiation ,Demagnetizing field ,Physics::Optics ,Heterojunction ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Condensed Matter::Materials Science ,Dipole ,Ferromagnetism ,Hall effect ,Condensed Matter::Strongly Correlated Electrons ,Thin film - Abstract
Spintronic thin films were shown to be promising high-performance broadband terahertz (THz) emitters. For spintronic ferromagnet/heavy metal heterostructures, THz emission arises from three mechanisms: the magnetic dipolar radiation due to the ultrafast demagnetization, the transient current radiation due to spin-charge conversion, and anomalous Hall effect. Here, we demonstrate that the three mechanisms show distinct dependences on the thickness of the ferromagnetic layer. With the insertion of an ultrathin ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ layer between the ferromagnetic and heavy metal layer, the spin-charge conversion is suppressed when the ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ thickness exceeds 1 nm. Our results agree with the theoretical predictions based on a simple spin-diffusion model.
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- 2021
6. Modulation of field-like spin orbit torque in heavy metal/ferromagnet heterostructures
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Houyi Cheng, Albert Fert, Weisheng Zhao, Zilu Wang, Jie Zhang, Daoqian Zhu, Junfeng Qiao, Kewen Shi, Dapeng Zhu, Sylvain Eimer, Wenlong Cai, Xueying Zhang, and Yang Liu
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Magnetoresistive random-access memory ,Materials science ,Condensed matter physics ,Magnetoresistance ,Annealing (metallurgy) ,Conductance ,Heterojunction ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Ferromagnetism ,0103 physical sciences ,Torque ,General Materials Science ,010306 general physics ,0210 nano-technology ,Ultrashort pulse - Abstract
Spin orbit torque (SOT) has drawn widespread attention in the emerging field of magnetic memory devices, such as magnetic random access memory (MRAM). To promote the performance of SOT-MRAM, most efforts have been devoted to enhance the SOT switching efficiency by improving the damping-like torque. Recently, some studies noted that the field-like torque also plays a crucial role in the nanosecond-timescale SOT dynamics. However, there is not yet an effective way to tune its relative amplitude. Here, we experimentally modulate the field-like SOT in W/CoFeB/MgO trilayers through tuning the interfacial spin accumulation. By performing spin Hall magnetoresistance measurement, we find that the CoFeB with enhanced spin dephasing, either generated from larger layer thickness or from proper annealing, can distinctly boost the spin absorption and enhance the interfacial spin mixing conductance Gr. While the damping-like torque efficiency increases with Gr, the field-like torque efficiency is found to decrease with it. The results suggest that the interfacial spin accumulation, which largely contributes to the field-like torque, is reduced by higher interfacial spin transparency. Our work shows a new path to further improve the performance of SOT-based ultrafast magnetic devices.
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- 2020
7. Highly anisotropic magnetic domain wall behavior in-plane magnetic films
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Sylvain Eimer, Ya Zhai, N. Vernier, Xiaochao Zhou, Weiwei Lin, and Guillaume Agnus
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Condensed Matter - Materials Science ,Materials science ,Field (physics) ,Magnetic domain ,Condensed matter physics ,Nucleation ,General Physics and Astronomy ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,01 natural sciences ,Magnetic field ,Condensed Matter::Materials Science ,Amplitude ,Ferromagnetism ,Zigzag ,0103 physical sciences ,010306 general physics ,Anisotropy ,Computer Science::Databases - Abstract
We have studied nucleation of magnetic domains and propagation of magnetic domain walls (DWs) induced by pulsed magnetic field in a ferromagnetic film with in-plane uniaxial anisotropy. Different from what have been seen up to now in out-of-plane anisotropy films, the nucleated domains have a rectangular shape in which a pair of the opposite sides are perfectly linear DWs, while the other pair present zigzags. This can be explained by magnetostatic optimization, knowing that the pulse field is applied parallel to the easy magnetization axis. The field induced propagation of these two DW types are very different. The linear ones follow a creep law identical to what is usually observed in out-of-plane films, when the velocity of zigzag DWs depends linearly on the applied field amplitude down to very low field. This most unusual feature can be explained by the shape of the DW, which makes it possible to go round the pinning defects. Thanks to that, it seems that propagation of zigzag walls agrees with the 1D model, and these results provide a first experimental evidence of the 1D model relevance in two dimensional ferromagnetic thin films. Let's note that it is the effective DW width parallel to DW propagation direction that matters in the 1D model formula, which is a relevant change when dealing with zigzag DWs., Comment: 20 pages, 13 figures
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- 2020
- Full Text
- View/download PDF
8. Spintronic terahertz emitter with integrated electromagnetic control
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Yunqing Jiang, Xiaoqiang Zhang, Yongshan Liu, Pierre Vallobra, Sylvain Eimer, Fan Zhang, Yinchang Du, Fengguang Liu, Yong Xu, and Weisheng Zhao
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Electrical and Electronic Engineering ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials - Published
- 2022
9. Giant Perpendicular Magnetic Anisotropy in Mo‐Based Double‐Interface Free Layer Structure for Advanced Magnetic Tunnel Junctions
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Boyu Zhang, Weisheng Zhao, Shouzhong Peng, Zilu Wang, Daoqian Zhu, Yong Xu, Kewen Shi, Jingle Chen, Kaihua Cao, Sylvain Eimer, Xinran Wang, Danrong Xiong, Zongxia Guo, and Houyi Cheng
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Materials science ,Condensed matter physics ,Interface (Java) ,Perpendicular magnetic anisotropy ,Layer (electronics) ,Electronic, Optical and Magnetic Materials - Published
- 2020
10. Reversible Charge-Transfer Doping in Graphene due to Reaction with Polymer Residues
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Weisheng Zhao, Chenxing Deng, Guillaume Agnus, Ivanka Barisic, Diana Dragoe, Dafiné Ravelosona, Claude Chappert, Sylvain Eimer, Abdelkarim Ouerghi, Debora Pierucci, and Weiwei Lin
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Materials science ,Dopant ,Graphene ,Annealing (metallurgy) ,Doping ,technology, industry, and agriculture ,Photochemistry ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Ion ,law.invention ,symbols.namesake ,General Energy ,law ,symbols ,Molecule ,Organic chemistry ,Physical and Theoretical Chemistry ,Raman spectroscopy ,Graphene nanoribbons - Abstract
Chemical doping in graphene due to polymer molecules adsorption has attracted much recent interest because of the modification of electrical, magnetic, and optical properties of graphene. We show a reversible charge-transfer doping effect in graphene due to the reaction with poly(methyl methacrylate) (PMMA) residues. By helium ion irradiation and vacuum annealing without introducing an external dopant, reversible shifts in Raman G and 2D bands are observed as well as the change in the relative 2D band intensity to the G band. Chemical bonds between functional groups from PMMA residues and graphene could be formed due to He+ ion irradiation, and the desorption of functional groups from graphene is dominant during the vacuum annealing process. Meanwhile, PMMA residue on the graphene surface is mostly removed and the surface morphology becomes smooth after irradiation and annealing. Both electrical conductance and Raman band shifts show nonmonotonic dependence on the dose density, which remains after anneali...
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- 2014
11. Phase-transition-induced large magnetic anisotropy change in VO2/(Co/Pt)2 heterostructure
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Guodong Wei, Xiaoyang Lin, Zhizhong Si, Na Lei, Yanxue Chen, Sylvain Eimer, and Weisheng Zhao
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Physics ,Coupling (electronics) ,Work (thermodynamics) ,Phase transition ,Magnetization ,Magnetic anisotropy ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Modulation ,Heterojunction ,Anisotropy ,human activities - Abstract
We report the phase-transition controlled magnetic anisotropy modulation in the (Co/Pt)2/VO2 heterostructure, where VO2 is introduced into the system to applied an interfacial strain by its metal-insulator transition. A large reversible modulation of the perpendicular magnetic anisotropy (PMA) reaching 38 kJ/m3 is observed during this process. The calculated energy density variation of interfacial anisotropy reaches 100 mJ/m2, which shows significant advantage over traditional modulation strategies. Further experimental results including magnetization change versus temperature, strain buffered modulation and pre-strained sample comparison prove that the interfacial coupling between VO2 and PMA layers plays a crucial role in this modulation. This work, demonstrating the great potential of phase-transition material in efficient magnetic anisotropy modulation, would benefit the exploration for low-power consumption devices.
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- 2019
12. Perpendicular magnetic anisotropy in piezoelectric- and dielectric–ferromagnetic heterostructures based on Co/Pt multilayers
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Na Lei, Philippe Lecoeur, Nicolas Vernier, Sylvain Eimer, Thibaut Devolder, Dafiné Ravelosona, Guillaume Agnus, Weiwei Lin, and J.-P. Adam
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Materials science ,Spintronics ,Condensed matter physics ,Magnetism ,Metals and Alloys ,Physics::Optics ,Heterojunction ,02 engineering and technology ,Surfaces and Interfaces ,Dielectric ,Coercivity ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,021001 nanoscience & nanotechnology ,7. Clean energy ,01 natural sciences ,Piezoelectricity ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,Ferromagnetism ,Electric field ,0103 physical sciences ,Materials Chemistry ,010306 general physics ,0210 nano-technology - Abstract
We have optimized the perpendicular magnetic anisotropy of piezoelectric/ferromagnetic and dielectric/ferromagnetic heterostructures based on Co/Pt multilayers. These hybrid systems are promising for electric field control of magnetism for applications to ultra-low power spintronics devices. Epitaxial (PbMg1/3Nb2/3O3)0.7-(PbTiO3)0.3 has been used for the piezoelectric layer and several dielectric layers (MgO, Al2O3, HfO2, Ta2O5 and TiO2) have been tested. We show that for both heterostructures perpendicular magnetic anisotropy of Co/Pt multilayers can be obtained with small coercivity.
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- 2013
13. Publisher's Note: Interfacial Dzyaloshinskii-Moriya interaction in perpendicularly magnetizedPt/Co/AlOxultrathin films measured by Brillouin light spectroscopy [Phys. Rev. B91, 180405(R) (2015)]
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Mohamed Belmeguenai, Sylvain Eimer, Joo-Von Kim, André Thiaville, Andrey Stashkevich, Thibaut Devolder, Yves Roussigné, J.-P. Adam, and S. M. Chérif
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Brillouin zone ,Materials science ,Condensed matter physics ,Perpendicular ,Condensed Matter Physics ,Spectroscopy ,Electronic, Optical and Magnetic Materials - Published
- 2015
14. Interfacial Dzyaloshinskii-Moriya interaction in perpendicularly magnetizedPt/Co/AlOxultrathin films measured by Brillouin light spectroscopy
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Sylvain Eimer, Joo-Von Kim, J.-P. Adam, Thibaut Devolder, S. M. Chérif, André Thiaville, Mohamed Belmeguenai, Yves Roussigné, and Andrey Stashkevich
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Brillouin zone ,Physics ,Condensed matter physics ,Spin wave ,Skyrmion ,Perpendicular ,Condensed Matter Physics ,Spectroscopy ,Spin (physics) ,Anisotropy ,Electronic, Optical and Magnetic Materials - Abstract
Spin waves in perpendicularly magnetized ${\text{Pt/Co/AlO}}_{x}/\text{Pt}$ ultrathin films with varying Co thicknesses (0.6--1.2 nm) have been studied with Brillouin light spectroscopy in the Damon-Eshbach geometry. The measurements reveal a pronounced nonreciprocal propagation, which increases with decreasing Co thickness. This nonreciprocity, attributed to an interfacial Dzyaloshinskii-Moriya interaction (DMI), is significantly stronger than asymmetries resulting from surface anisotropies for such modes. Results are consistent with an interfacial DMI constant ${D}_{\mathrm{s}}=\ensuremath{-}1.7\ifmmode\pm\else\textpm\fi{}0.11\phantom{\rule{0.28em}{0ex}}\text{pJ}$/m, which favors left-handed chiral spin structures. This suggests that such films below 1 nm in thickness should support chiral states such as skyrmions at room temperature.
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- 2015
15. Erratum: 'Influence of heavy metal materials on magnetic properties of Pt/Co/heavy metal tri-layered structures' [Appl. Phys. Lett. 110, 012405 (2017)]
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Mingzhong Wu, Sylvain Eimer, Zhaohao Wang, Weisheng Zhao, Kaihua Cao, Na Lei, Xiaoxuan Zhao, Boyu Zhang, Minghong Tang, Anni Cao, Zhizhong Si, Junfeng Qiao, Zongzhi Zhang, and Xiaoyang Lin
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010302 applied physics ,Materials science ,Physics and Astronomy (miscellaneous) ,chemistry.chemical_element ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Metal ,chemistry ,visual_art ,0103 physical sciences ,visual_art.visual_art_medium ,Physical chemistry ,0210 nano-technology ,Platinum ,Cobalt - Published
- 2017
16. Influence of heavy metal materials on magnetic properties of Pt/Co/heavy metal tri-layered structures
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Mingzhong Wu, Kaihua Cao, Zongzhi Zhang, Xiaoxuan Zhao, Xiaoyang Lin, Zhaohao Wang, Boyu Zhang, Weisheng Zhao, Anni Cao, Junfeng Qiao, Na Lei, Minghong Tang, Sylvain Eimer, and Zhizhong Si
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Materials science ,Kerr effect ,Physics and Astronomy (miscellaneous) ,Perpendicular magnetic anisotropy ,Magnetometer ,FOS: Physical sciences ,02 engineering and technology ,01 natural sciences ,law.invention ,Metal ,law ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,0103 physical sciences ,Coupling (piping) ,010306 general physics ,Physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed matter physics ,Spintronics ,Skyrmion ,021001 nanoscience & nanotechnology ,Magnetic anisotropy ,Domain wall (magnetism) ,Chemical physics ,visual_art ,visual_art.visual_art_medium ,0210 nano-technology ,Layer (electronics) - Abstract
Pt/Co/heavy metal (HM) tri-layered structures with interfacial perpendicular magnetic anisotropy (PMA) are currently under intensive research for several emerging spintronic effects, such as spinorbit torque, domain wall motion, and room temperature skyrmions. HM materials are used as capping layers to generate the structural asymmetry and enhance the interfacial effects. For instance, the Pt/Co/Ta structure attracts a lot of attention as it may exhibit large Dzyaloshinskii-Moriya interaction. However, the dependence of magnetic properties on different capping materials has not been systematically investigated. In this paper, we experimentally show the interfacial PMA and damping constant for Pt/Co/HM tri-layered structures through time-resolved magneto-optical Kerr effect measurements as well as magnetometry measurements, where the capping HM materials are W, Ta, and Pd. We found that the Co/HM interface plays an important role on the magnetic properties. In particular, the magnetic multilayers with a W capping layer features the lowest effective damping value, which may be attributed to the different spin-orbit coupling and interfacial hybridization between Co and HM materials. Our findings allow a deep understanding of the Pt/Co/HM tri-layered structures. Such structures could lead to a better era of data storage and processing devices., 6 pages, 5 figures, 2 tables
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- 2017
17. Measurement of magnetization using domain compressibility in CoFeB films with perpendicular anisotropy
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Thibaut Devolder, Guillaume Agnus, Thomas Hauet, Sylvain Eimer, J-P Adam, Francielle P. Garcia, Dafiné Ravelosona, N. Vernier, Berthold Ocker, Institut d'électronique fondamentale (IEF), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Institut Jean Lamour (IJL), Institut de Chimie du CNRS (INC)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), and Singulus technology AG
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Condensed Matter - Materials Science ,Materials science ,Condensed Matter - Mesoscale and Nanoscale Physics ,Physics and Astronomy (miscellaneous) ,Spintronics ,Field (physics) ,Condensed matter physics ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,Magnetization ,Dipole ,Condensed Matter::Materials Science ,Condensed Matter::Superconductivity ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Domain (ring theory) ,Compressibility ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] ,Perpendicular anisotropy ,Metallic thin films - Abstract
Équipe 101 : Nanomagnétisme et électronique de spin; International audience; We present a method to map the saturation magnetization of soft ultrathin films with perpendicular anisotropy, and we illustrate it to assess the compositional dependence of the magnetization of CoFeB(1 nm)/MgO films. The method relies on the measurement of the dipolar repulsion of parallel domain walls that define a linear domain. The film magnetization is linked to the field compressibility of the domain. The method also yields the minimal distance between two walls before their merging, which sets a practical limit to the storage density in spintronic devices using domain walls as storage entities.
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- 2014
18. Raman spectroscopy study of low energy He+ ion irradiation effect in graphene transferred onto SiO2
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Chenxing Deng, Dafiné Ravelosona, Claude Chappert, Weiwei Lin, Sylvain Eimer, and Weisheng Zhao
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chemistry.chemical_classification ,Materials science ,Physics::Instrumentation and Detectors ,Graphene ,Doping ,Analytical chemistry ,Chemical vapor deposition ,Polymer ,law.invention ,Ion ,symbols.namesake ,Low energy ,chemistry ,law ,symbols ,Irradiation ,Raman spectroscopy - Abstract
We studied the low energy (5.4 keV) He+ ion irradiation effect on the properties of chemical vapor deposited graphene transferred onto SiO2/Si substrate. For a small dose density of 4 × 1012 He+/cm2, both the G and 2D bands in the Raman spectra exhibit blue-shift and the intensity ratio of the 2D and G peaks decreases. The intensity ratio of the D and G peaks increases a lot as the dose density is larger than 1.2 × 1013 He+/cm2. It suggests that before the formation of large amount of defects, low energy He+ ion irradiation may induce charge-transfer doping in graphene due to the presence of polymer residues. Broad spatial distributions of the band shift and the intensity ratio indicate inhomogeneity of doping level in graphene.
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- 2013
19. Compositional dependence of the magnetic properties of epitaxial FeV/MgO thin films
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Sylvain Eimer, Thibaut Devolder, Thomas Hauet, Taiebeh Tahmasebi, Stéphane Andrieu, IEF, Université Paris-Sud - Paris 11 (UP11), IMEC (IMEC), Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Institut Jean Lamour (IJL), and Université de Lorraine (UL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
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010302 applied physics ,Materials science ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Alloy ,engineering.material ,Epitaxy ,01 natural sciences ,Ferromagnetic resonance ,Magnetic anisotropy ,Magnetization ,Condensed Matter::Materials Science ,Lattice (order) ,Condensed Matter::Superconductivity ,0103 physical sciences ,engineering ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] ,Thin film ,010306 general physics ,Anisotropy - Abstract
International audience; Owing to their bcc structures and the low lattice misfit with MgO, FeV alloys are interesting for MgO-based magnetic tunnel junctions. We use vector network analyzer ferromagnetic resonance to measure the magnetization, anisotropy, exchange stiffness, and damping of epitaxial FeV/MgO thin alloys of various V contents. The low magnetization, very high exchange stiffness (23 pJ/m) and very low effective damping (
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- 2013
20. Controlling magnetic domain wall motion in the creep regime in He+-irradiated CoFeB/MgO films with perpendicular anisotropy
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Felipe Garcia-Sanchez, L. Herrera Diez, Alessio Lamperti, Dafiné Ravelosona, Thibaut Devolder, Berthold Ocker, Sylvain Eimer, M. S. El Hadri, R. Mantovan, and J.-P. Adam
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Materials science ,Physics and Astronomy (miscellaneous) ,Magnetic domain ,Condensed matter physics ,ion irradiation ,Physics::Medical Physics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Magnetic field ,Condensed Matter::Materials Science ,Magnetization ,Magnetic anisotropy ,Creep ,Condensed Matter::Superconductivity ,0103 physical sciences ,Irradiation ,010306 general physics ,0210 nano-technology ,Anisotropy ,Saturation (magnetic) ,CoFeB ,PMA - Abstract
This study presents the effective tuning of perpendicular magnetic anisotropy in CoFeB/MgO thin films by He+ ion irradiation and its effect on domain wall motion in a low field regime. Magnetic anisotropy and saturation magnetisation are found to decrease as a function of the irradiation dose which can be related to the observed irradiation-induced changes in stoichiometry at the CoFeB/MgO interface. These changes in the magnetic intrinsic properties of the film are reflected in the domain wall dynamics at low magnetic fields (H) where irradiation is found to induce a significant decrease in domain wall velocity (v). For all irradiation doses, domain wall velocities at low fields are well described by a creep law, where Ln(v) vs. H-1/4 behaves linearly, up to a maximum field H*, which has been considered as an approximation to the value of the depinning field Hdep. In turn, H*Hdep is seen to increase as a function of the irradiation dose, indicating an irradiation-induced extension of the creep regime of domain wall motion.
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- 2015
21. 1-D laser beam shaping using an adjustable binary diffractive optical element
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Michael Fromager, Sylvain Eimer, C. Gunther, Nicolas Passilly, Tayeb Mohammed-Brahim, Laurence Méchin, Kamel Ait-Ameur, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), 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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), 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)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Equipe Electronique - Laboratoire GREYC - UMR6072, Groupe de Recherche en Informatique, Image et Instrumentation de Caen (GREYC), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Histologie et de Pathologie moléculaire des tumeurs, Université Bordeaux Segalen - Bordeaux 2-EA 2406, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), 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), Normandie Université (NU)-Normandie Université (NU)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Kervella, Katell, and Université de Nantes (UN)-Université de Rennes 1 (UR1)
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Diffraction ,Physics ,Beam diameter ,business.industry ,Phase (waves) ,Physics::Optics ,Binary number ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Slit ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,010309 optics ,Transformation (function) ,Optics ,0103 physical sciences ,M squared ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,0210 nano-technology ,business ,ComputingMilieux_MISCELLANEOUS ,Gaussian beam - Abstract
We present a theoretical and experimental investigation of a very simple binary Diffractive Optical element referred as a phase slit. The latter is made up of two transparent plates of glass in which a phase step has been patterned using ion beam etching. The two phase steps are set parallel and are able to slide each on the other so that one can adjust continuously the width of the phase shifting zone that suffers an incident Gaussian beam. It is shown that the phase slit is able to make a 1-D transformation of a Gaussian beam either into a uniform profile or a hollow profile having a central depression whose depth can be continuously adjusted just by changing the width of the slit.
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- 2004
22. Low depinning fields in Ta-CoFeB-MgO ultrathin films with perpendicular magnetic anisotropy
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Sylvain Eimer, L. Herrera Diez, R. Mantovan, I. Barisic, C. Burrowes, Alessio Lamperti, Dafiné Ravelosona, Eric E. Fullerton, Joo-Von Kim, J.-P. Adam, Thibaut Devolder, Karin Garcia, B. Ockert, Guillaume Agnus, and N. Vernier
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Materials science ,Physics and Astronomy (miscellaneous) ,Spintronics ,Magnetic domain ,Condensed matter physics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Amorphous solid ,Magnetic field ,Condensed Matter::Materials Science ,Magnetic anisotropy ,Ferromagnetism ,Magnetic shape-memory alloy ,Condensed Matter::Superconductivity ,0103 physical sciences ,Perpendicular ,010306 general physics ,0210 nano-technology - Abstract
We have studied the domain-wall dynamics in Ta-CoFeB-MgO ultra-thin films with perpendicular magnetic anisotropy for various Co and Fe concentrations in both the amorphous and crystalline states. We observe three motion regimes with increasing magnetic field, which are consistent with a low fields creep, transitory depinning, and high fields Walker wall motion. The depinning fields are found to be as low as 2 mT, which is significantly lower than the values typically observed in 3d ferromagnetic metal films with perpendicular magnetic anisotropy. This work highlights a path toward advanced spintronics devices based on weak random pinning in perpendicular CoFeB films.
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- 2013
23. Irradiation-induced tailoring of the magnetism of CoFeB/MgO ultrathin films
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Thibaut Devolder, Karin Garcia, Dafiné Ravelosona, Sylvain Eimer, I. Barisic, J.-P. Adam, and B. Ockert
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010302 applied physics ,Materials science ,Condensed matter physics ,Magnetism ,Annealing (metallurgy) ,General Physics and Astronomy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Fluence ,law.invention ,Magnetization ,Magnetic anisotropy ,Nuclear magnetic resonance ,law ,0103 physical sciences ,Astrophysics::Earth and Planetary Astrophysics ,Irradiation ,Crystallization ,0210 nano-technology ,Anisotropy - Abstract
We study perpendicularly magnetized Ta/CoFeB/MgO films and investigate whether their irradiation with light ions can improve their properties by inducing a different crystallization dynamics. We report the magnetization, anisotropy, g-factor, and damping dependence upon irradiation fluence and discuss their evolutions with collisional mixing simulations and its expected consequence on magnetic properties. We show that after a short irradiation at 100 °C, the anisotropy increases close to the value obtained by conventional high temperature annealing. Higher irradiation-induced increase of anisotropy can be obtained but with a detrimental effect on the damping that can be understood from spin-orbit contributions.
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- 2013
24. Configuration and temperature dependence of magnetic damping in spin valves
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Sylvain Eimer, Joo-Von Kim, Thibaut Devolder, Y. Gomez de la Torre, X. Joyeux, and Claude Chappert
- Subjects
Permalloy ,Condensed Matter::Materials Science ,Magnetization ,Spin pumping ,Exchange bias ,Condensed matter physics ,Chemistry ,Magnetic damping ,Spin valve ,General Physics and Astronomy ,Ferromagnetic resonance ,Magnetic susceptibility - Abstract
Using vector-analyzer ferromagnetic resonance, we have studied the microwave susceptibility of a Py/Co/Cu/Co/MnIr spin valve over a large temperature range (5-450 K) and as a function of the magnetic configuration. An effective magnetization and Gilbert damping constant of 1.1 T and 0.021, respectively, are found for the permalloy free layer, with no discernible variation in temperature observed for either quantities. In contrast, the pinned layer magnetization is reduced by heating, and the exchange bias collapses near a temperature of 450 K. The ferromagnetic resonance linewidth of the free layer increases by 500 MHz when the layer magnetizations are aligned in antiparallel, which is attributed to a configuration-dependent contribution to the damping from spin pumping effects.
- Published
- 2011
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