Article
Chemistry, Multidisciplinary
Maria Ameziane, Rhodri Mansell, Ville Havu, Patrick Rinke, Sebastiaan van Dijken
Summary: This study demonstrates the reversible voltage-controlled switching between perpendicular and in-plane magnetization states in a Co-Pt bilayer using solid-state lithium-ion battery technology. Due to the small size and high mobility of lithium ions, small voltages produce an exceptionally high magnetoelectric coupling efficiency. The magnetic switching effect is attributed to the modulation of spin-orbit coupling at the Co-Pt interface when lithium ions migrate between a lithium storage layer and the magnetic interface across a solid-state electrolyte.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Multidisciplinary Sciences
Xin Yu Zheng, Sanyum Channa, Lauren J. Riddiford, Jacob J. Wisser, Krishnamurthy Mahalingam, Cynthia T. Bowers, Michael E. McConney, Alpha T. N'Diaye, Arturas Vailionis, Egecan Cogulu, Haowen Ren, Zbigniew Galazka, Andrew D. Kent, Yuri Suzuki
Summary: This study introduces a ferromagnetic insulator spinel, Li0.5Al1.0Fe1.5O4 (LAFO), with low magnetic damping, perpendicular magnetic anisotropy, and no magnetic dead layer. By integrating these LAFO films with epitaxial Pt spin source layers, record low magnetization switching currents and high spin-orbit torque efficiencies are achieved.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Xi Chen, Shao-Long Jiang, Dong-Wei Wang, Kang Yang, Jin-Hui Lu, Guang-Hua Yu
Summary: The effect of ultrathin Fe layer on perpendicular magnetic anisotropy (PMA) in Co/Pt multilayers was investigated. The position of the Fe layer at the interface strongly influenced the PMA. When the Fe layer was doped at the Co/Pt interface, the PMA decreased monotonically with increasing Fe layer thickness. However, when the Fe layer was doped at the Pt/Co interface, the PMA showed a peak at a specific thickness. The variation in PMA is mainly attributed to the tuning of electron occupation states at Fe-doped Pt/Co interface.
Article
Physics, Applied
G. Kopnov, A. Gerber
Summary: The coercive field of laterally heterogeneous CoPd films with perpendicular magnetic anisotropy is highly sensitive to their nominal thickness and morphology in the vicinity of the metal-insulator transition. We used this effect to tune the coercivity by adjusting the width of lithographically patterned stripes with non-uniform cross-sectional thickness profiles, providing a method to control the local anisotropy of spintronic logic circuitry elements using their shape and lateral dimensions.
APPLIED PHYSICS LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Meng Zhao, Lei Wang, Yifan Zhao, Yujing Du, Zhexi He, Kai Chen, Zhenlin Luo, Wensheng Yan, Qian Li, Chenying Wang, Zhuangde Jiang, Ming Liu, Ziyao Zhou
Summary: Researchers propose an energy-efficient method for switching magnetization in spintronic devices using sunlight control. By inducing photoelectron-induced redistribution of the orbital and spin moment, the in-plane Rashba field is enhanced, leading to a weakened perpendicular magnetic anisotropy and magnetization switching. This sunlight control of PMA could offer an alternative way for energy-efficient magnetic recording.
Article
Materials Science, Multidisciplinary
H. Xia, Z. R. Zhao, F. L. Zeng, H. C. Zhao, J. Y. Shi, Z. Zheng, X. Shen, J. He, G. Ni, Y. Z. Wu, L. Y. Chen, H. B. Zhao
Summary: The study investigates the influence of magnetization orientation on Gilbert damping and ultrafast demagnetization in single-crystalline Co50Fe50 films, revealing a significant anisotropy in Gilbert damping but nearly isotropic behavior in ultrafast demagnetization across different in-plane magnetization orientations.
Article
Physics, Applied
Pravin Khanal, Bowei Zhou, Magda Andrade, Yanliu Dang, Albert Davydov, Ali Habiboglu, Jonah Saidian, Adam Laurie, Jian-Ping Wang, Daniel B. Gopman, Weigang Wang
Summary: Perpendicular magnetic tunnel junctions with composite free layers have been studied, showing a strong dependence of tunneling magnetoresistance on the thickness of the first CoFeB layer. When Mo and MgO are used as coupling layers, a large tunneling magnetoresistance above 200% has been achieved after 400°C annealing.
APPLIED PHYSICS LETTERS
(2021)
Article
Chemistry, Physical
Rocio M. Gutierrez-Perez, Diego I. Zubiate-Perez, Ricardo Lopez Anton, Maria E. Fuentes-Montero, Jose T. Holguin-Momaca, Oscar O. Solis-Canto, Adriana Alvidrez-Lechuga, Juan Antonio Gonzalez, Sion F. Olive-Mendez
Summary: This study provides a comprehensive analysis of the magnetization and effective perpendicular magnetic anisotropy (PMA) of epitaxial D0(22)-Mn3+xGa ultrathin films. The growth method significantly affects the uniaxial PMA and thickness of non-magnetic layers, while the saturation magnetization remains unchanged. These results can be explained by interface structural defects caused by lattice mismatch and growth method.
SURFACES AND INTERFACES
(2022)
Article
Chemistry, Physical
Y. Q. Guo, H. Bai, Q. R. Cui, L. M. Wang, Y. C. Zhao, X. Z. Zhan, T. Zhu, H. X. Yang, Y. Gao, C. Q. Hu, S. P. Shen, C. L. He, S. G. Wang
Summary: The effect of vacuum annealing on the perpendicular magnetic anisotropy of MgO/CoFeB/VV stacks was studied, showing that the PMA can be well maintained at 590 degrees C. Furthermore, there was significant segregation of Co and Fe atoms at the CoFeB/W interface after annealing at this temperature.
APPLIED SURFACE SCIENCE
(2021)
Article
Polymer Science
Karthika Madathil, Banafsheh Hekmatnia, Haleh Ardebili, Gila E. Stein
Summary: This study examines the impact of solvent composition and solution-casting process on the structure and properties of a lamellar sulfonated pentablock copolymer (SPC) membrane. The results show that sequential deposition of multiple layers can predict the structure of dry films and processing conditions strongly influence through-plane transport properties. This study provides valuable insights for optimizing critical transport properties.
Article
Materials Science, Multidisciplinary
Ashok Pokhrel, Bhuwan Nepal, Upama Karki, Arjun Sapkota, Anish Rai, Sara Bey, Tim Mewes, Claudia Mewes
Summary: This article investigates the influence of layer dependent second-order perpendicular anisotropy on higher-order anisotropies in thin films using a macrospin model. The study finds that the origin of the fourth-order anisotropy is linked to the layer-wise variation of magnetization direction, resulting in a dependence on field strength and exchange stiffness. Furthermore, it is observed that the apparent fourth-order anisotropy increases with decrease in exchange stiffness.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Ke Wang, Yongming Tang, Xiaopeng Xiao, Zhan Xu, Jian Liu
Summary: TbFeCo alloy films with adjustable coercivity and perpendicular magnetic anisotropy can be achieved by controlling the sputtering power and gas flow rate during fabrication. Proper tuning of these parameters allows for the optimization of the films' magnetic properties, which is crucial for the design of high-density spintronic devices.
JOURNAL OF MATERIALS SCIENCE
(2021)
Article
Chemistry, Physical
Xiaoyue Liu, Xiaodong Yang, Jueming Yang, Pingji Ge, Hongxia Yan, Jianguo Wan, Guixian Ge, Guanghou Wang
Summary: This study demonstrates the potential to enhance magnetic anisotropy by functionalizing a single W atom with hydroxy radicals on the MgO/Ag heterojunction. The resulting system exhibits a remarkable perpendicular MAE and provides a promising approach for high-density information storage devices at the nanoscale.
APPLIED SURFACE SCIENCE
(2021)
Article
Nanoscience & Nanotechnology
Liang Liu, Chenghang Zhou, Xinyu Shu, Changjian Li, Tieyang Zhao, Weinan Lin, Jinyu Deng, Qidong Xie, Shaohai Chen, Jing Zhou, Rui Guo, Han Wang, Jihang Yu, Shu Shi, Ping Yang, Stephen Pennycook, Aurelien Manchon, Jingsheng Chen
Summary: An out-of-plane spin-orbit torque (SOT) has been observed in an HM/FM bilayer of CuPt/CoPt, referred to as 3m torque, allowing for field-free switching of perpendicular magnetization of the CoPt layer. The 3m torque depends strongly on the relative orientation of current flow and crystal symmetry, and shows good endurance in cycling experiments. Experiments with various SOT bilayers featuring low-symmetry point groups at the interface may reveal further unconventional spin torques in the future.
NATURE NANOTECHNOLOGY
(2021)
Article
Physics, Multidisciplinary
Shuyao Chen, Yunfei Xie, Yucong Yang, Dong Gao, Donghua Liu, Lin Qin, Wei Yan, Bi Tan, Qiuli Chen, Tao Gong, En Li, Lei Bi, Tao Liu, Longjiang Deng
Summary: In this study, we addressed the challenge of achieving perpendicular magnetic anisotropy (PMA) in yttrium iron garnet (YIG) films thicker than 20 nm. By using substrates with moderate lattice mismatch, we successfully suppressed the excessive strain-induced stress release and achieved out-of-plane spontaneous magnetization even in YIG films as thick as 50 nm. Ferromagnetic resonance and spin pumping induced inverse spin Hall effect measurements confirmed the good spin transparency at the surface of our YIG films.
Article
Physics, Applied
Lijun Zhu, Lujun Zhu, D. C. Ralph, R. A. Buhrman
PHYSICAL REVIEW APPLIED
(2020)
Article
Chemistry, Multidisciplinary
Lijun Zhu, Xiyue S. Zhang, David A. Muller, Daniel C. Ralph, Robert A. Buhrman
ADVANCED FUNCTIONAL MATERIALS
(2020)
Article
Physics, Multidisciplinary
Lijun Zhu, Lujun Au, Robert A. Buhrman
Summary: By inserting an insulating paramagnetic NiO layer of optimum thickness at Pt-based heavy metal-ferromagnet interfaces, spin backflow and spin-memory loss can be effectively eliminated, resulting in significantly enhanced spin-current transmission efficiency and improved spin-torque efficiency for related technologies.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Applied
Lijun Zhu, D. C. Ralph, R. A. Buhrman
Summary: Research shows that there is no simple correlation between the efficiency of dampinglike spin orbit torque and the critical switching current density of perpendicularly magnetized spin-current generator-ferromagnet heterostructures, especially in micrometer-sized samples. The values of efficiency based on switching current densities can sometimes severely underestimate or overestimate the actual efficiency, making critical switching current densities alone a poor predictor of the relative strength of spin-current generators.
PHYSICAL REVIEW APPLIED
(2021)
Article
Physics, Applied
Lijun Zhu, Robert A. Buhrman
Summary: After a decade of intensive theoretical and experimental explorations, it remains in dispute whether interfacial spin-orbit coupling at metallic magnetic interfaces can effectively generate a spin current. Utilizing Ti/Fe-Co-B bilayers with unique properties, the study found no significant charge-to-spin conversion at magnetic interfaces, even with stronger ISOC than a typical Pt/ferromagnet interface. Additionally, a minimal orbital Hall effect was observed in 3d Ti.
PHYSICAL REVIEW APPLIED
(2021)
Article
Chemistry, Multidisciplinary
Lijun Zhu, Daniel C. Ralph, Robert A. Buhrman
Summary: The study investigates the mechanism of unexpected bulk spin-orbit torques (SOTs) in magnetic single-layers by utilizing chemically disordered FexPt1-x. It is found that the bulk dampinglike SOT arises from an imbalanced internal spin current and is sensitive to the presence of a vertical composition gradient. The discovery suggests the potential development of low-power single-layer SOT devices through strain engineering.
ADVANCED FUNCTIONAL MATERIALS
(2021)
Review
Physics, Applied
Lijun Zhu, Daniel C. Ralph, Robert A. Buhrman
Summary: Platinum, with its giant spin Hall conductivity and compatibility with CMOS circuits, has the potential to be an outstanding provider of spin-orbit torques; however, pure clean-limit Pt with low resistivity still provides a low damping-like spin-orbit torque efficiency, limiting its practical applications; the efficiency of spin-orbit torque in Pt-based magnetic heterostructures can be significantly improved by increasing the spin Hall ratio of Pt and the spin transmissivity of the interfaces.
APPLIED PHYSICS REVIEWS
(2021)
Article
Physics, Applied
Qianbiao Liu, Lijun Zhu, Xiyue S. Zhang, David A. Muller, Daniel C. Ralph
Summary: This study reports a distinct and giant bulk damping-like spin-orbit torque in strong-perpendicular magnetic anisotropy (PMA) ferrimagnetic Fe100-xTbx single layers. The giant bulk torque can switch thick Fe100-xTbx layers with very strong PMA and high coercivity at low current densities.
APPLIED PHYSICS REVIEWS
(2022)
Article
Physics, Multidisciplinary
Lijun Zhu, Lujun Zhu, Xin Ma, Xiaoqin Li, Robert A. Buhrman
Summary: In this paper, the authors quantitatively establish the roles of orbital hybridization and interfacial spin-orbit coupling (ISOC) in the determination of Dzyaloshinskii-Moriya interaction (DMI), and propose orbital hybridization as a degree of freedom for the development of fast, dense spintronic memory and computing technologies. Through their study of the model magnetic interface Au1-xPtx/Co, they find that DMI, ISOC, and orbital hybridization can be quantified and tuned significantly at the same time by varying the composition of the Au1-xPtx. This research provides a quantitative framework for understanding interfacial DMI of various magnetic interfaces and establishes orbital hybridization as a new degree of freedom for controlling DMI.
COMMUNICATIONS PHYSICS
(2022)
Article
Physics, Applied
Qianbiao Liu, Lijun Zhu
Summary: In this study, we report the discovery and profound impacts of a significant effective perpendicular magnetic field that can arise from asymmetric current spreading within magnetic microstrips and Hall bars. This finding challenges the widely assumed characteristics of an external-magnetic-field-free flow of sigma(z), and highlights the importance of considering current spreading effects in the analysis of spin polarizations and spin-orbit torques in magnetic heterostructures. Technologically, our results provide a novel and universally accessible mechanism for efficient, scalable, and external-magnetic-field-free magnetization switching in memory and computing technologies.
APPLIED PHYSICS REVIEWS
(2022)
Article
Physics, Applied
Qianbiao Liu, Jingwei Li, Lujun Zhu, Xin Lin, Xinyue Xie, Lijun Zhu
Summary: By studying the spin-orbit torque in Cr1-xPtx alloys, we have found that the dampinglike spin-orbit torque can be enhanced by tuning the Cr concentration in the Cr1-xPtx layer. The trade-off between the intrinsic spin Hall conductivity of Pt and the spin carrier lifetime in the dirty limit fully explains the mechanism and efficiency of spin-current generation in the Cr1-xPtx alloy.
PHYSICAL REVIEW APPLIED
(2022)
Article
Physics, Applied
Lijun Zhu, Jingwei Li, Lujun Zhu, Xinyue Xie
Summary: This article introduces a method for efficient manipulation of magnetic materials, in which the stacking of superlattices with inversion-symmetry breaking can significantly enhance the efficiency of spin-orbit torques. This method allows for the achievement of perpendicular magnetic anisotropy in thick magnetic layers and enables the switching of such layers with lower power consumption.
PHYSICAL REVIEW APPLIED
(2022)
Article
Multidisciplinary Sciences
Lijun Zhu, Daniel C. Ralph
Summary: Spin-orbit torques acting on ferrimagnetic FexTb1-x layers decrease and vanish upon approaching the magnetic compensation point due to the competing spin relaxation processes. The relative rates of spin relaxation within magnetic layers play a critical role in determining the strength of SOTs, providing a unified understanding for diverse SOT phenomena. It is important to minimize spin-orbit scattering within the magnet for efficient SOT devices, and the interfacial spin-mixing conductance of ferrimagnetic alloys is large and insensitive to magnetic compensation.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Qianbiao Liu, Xin Lin, Lijun Zhu
Summary: This study found no evidence of spin current with any spin polarizations from the interface or bulk of single-crystalline CoFe. The sin2φ second harmonic Hall voltage, previously assumed to signify Dresselhaus-like spin current, is actually a planar Nernst voltage induced by a longitudinal temperature gradient within the sample. This signal is independent of large applied magnetic fields and interfacial spin-orbit coupling, inversely correlated to the heat capacity of the substrates and overlayers, quadratic in charge current, and appears also in polycrystalline ferromagnets. The strong fourfold anisotropic planar Nernst effect in the CoFe single crystal has widespread impacts on the analyses of various spintronic experiments and opens a new avenue for the development of PNE-based thermoelectric battery and sensor applications.
Article
Materials Science, Multidisciplinary
Xin Lin, Jingwei Li, Lujun Zhu, Xinyue Xie, Qianbiao Liu, Dahai Wei, Guodong Yuan, Lijun Zhu
Summary: We report a strong enhancement of spin-orbit torques in dirty metal Pt by incorporating Si3N4 impurities. The enhancement is attributed to the optimized trade-off between the intrinsic spin Hall conductivity and the spin carrier lifetime in the dirty limit, resulting in a twofold increase in the dampinglike spin-orbit torque per unit current density in Pt-x(Si3N4)(1-x)/Co0.65Tb0.35 bilayers. We also find that only 58% of the angular momentum of the spin current contributes to spin torque generation.
