Article
Chemistry, Multidisciplinary
Xiaoxi Huang, Shehrin Sayed, Joseph Mittelstaedt, Sandhya Susarla, Saba Karimeddiny, Lucas Caretta, Hongrui Zhang, Vladimir A. Stoica, Tanay Gosavi, Farzad Mahfouzi, Qilong Sun, Peter Ercius, Nicholas Kioussis, Sayeef Salahuddin, Daniel C. Ralph, Ramamoorthy Ramesh
Summary: The research shows that epitaxial LSMO/SIO heterostructures grown on STO substrates exhibit a high SOT efficiency and help increase the effective magnetization of LSMO. These findings highlight the importance of epitaxy as a powerful tool to achieve high SOT efficiency and explore new pathways for designing next-generation energy-efficient spintronic devices.
ADVANCED MATERIALS
(2021)
Article
Engineering, Electrical & Electronic
Yakun Liu, Guoyi Shi, Dushyant Kumar, Taeheon Kim, Shuyuan Shi, Dongsheng Yang, Jiantian Zhang, Chenhui Zhang, Fei Wang, Shuhan Yang, Yuchen Pu, Peng Yu, Kaiming Cai, Hyunsoo Yang
Summary: In this study, we report the field-free switching of perpendicular magnetic anisotropy ferromagnet cobalt iron boron using out-of-plane spin-polarized current generated by the Weyl semimetal tantalum iridium telluride. Our results suggest that TaIrTe4 is an efficient spin current source for field-free spin-orbit torque applications.
NATURE ELECTRONICS
(2023)
Article
Nanoscience & Nanotechnology
Yong-Chang Lau, Takeshi Seki, Koki Takanashi
Summary: This study presents a systematic comparative analysis of spin Hall efficiency in highly face-centered cubic (fcc) Pt-Al alloy films and poorly crystallized Pt-Al alloy films. The results indicate that fcc Pt100-xAlx alloy films grown on MgO exhibit outstanding charge-spin conversion efficiency, showing the potential for reducing power consumption compared to polycrystalline bilayers on SiO2. Improving the crystallinity of fcc Pt-based alloys is shown to be crucial for achieving large spin Hall efficiency and low power consumption.
Article
Materials Science, Multidisciplinary
Xiang Li, Peng Li, Vincent D-H Hou, D. C. Mahendra, Chih-Hung Nien, Fen Xue, Di Yi, Chong Bi, Chien-Min Lee, Shy-Jay Lin, Wilman Tsai, Yuri Suzuki, Shan X. Wang
Summary: Disordered sputtered WTex thin films exhibit local chemical and structural order similar to Weyl semimetal WTe2, with properties consistent with semimetallic Weyl fermion behavior. Thermally annealed sputtered WTex films show large charge-to-spin conversion properties and electrical conductivity comparable to crystalline WTe2 flakes, with significant unidirectional spin Hall magnetoresistance in heterostructures. Furthermore, room-temperature damping-like SOT-driven magnetization switching of in-plane magnetized CoFeB is demonstrated in the study.
Article
Physics, Applied
Fu Liu, Jinli Yao, Chenglong Jia, Changjun Jiang
Summary: By changing the direction of applied radio frequency microwave currents, we demonstrate a significant conversion anisotropy of up to 400% in fourfold-symmetric anisotropy Fe films on MgO(100) substrate. The fourfold-symmetric anisotropy stems from large emergent spin-orbit coupling in Fe films with local lattice distortions. Our findings provide a simple route for designing future energy-efficient magnetic devices.
PHYSICAL REVIEW APPLIED
(2023)
Article
Chemistry, Multidisciplinary
Weihao Li, Wenkai Zhu, Gaojie Zhang, Hao Wu, Shouguo Zhu, Runze Li, Enze Zhang, Xiaomin Zhang, Yongcheng Deng, Jing Zhang, Lixia Zhao, Haixin Chang, Kaiyou Wang
Summary: In this study, the perpendicular magnetization of the vdW ferromagnet Fe3GaTe2 was successfully switched at room temperature using spin-orbit torques with a relatively low current density. The high efficiency of this method, quantitatively determined by harmonic measurements, provides a significant basis for the development of vdW-ferromagnet-based spintronic applications.
ADVANCED MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Takeshi Seki, Yong-Chang Lau, Satoshi Iihama, Koki Takanashi
Summary: The study evaluated the self-induced spin-orbit torque in a single ferromagnetic layer, showing that spin-torque ferromagnetic resonance was present in thin Ni-Fe layers with both asymmetric and symmetric Py layers, while the dampinglike torque was observed only in asymmetric Py layers with thickness <= 3 nm.
Article
Multidisciplinary Sciences
Binoy K. Hazra, Banabir Pal, Jae-Chun Jeon, Robin R. Neumann, Boerge Goebel, Bharat Grover, Hakan Deniz, Andriy Styervoyedov, Holger Meyerheim, Ingrid Mertig, See-Hun Yang, Stuart S. P. Parkin
Summary: The generation of a robust spin current with both in-plane and out-of-plane spin polarization is demonstrated in epitaxial thin films of the chiral antiferromagnet Mn3Sn in proximity to permalloy thin layers. The in-plane polarized spin current is generated from the interior of Mn3Sn and follows its temperature dependence, while the out-of-plane polarized spin current arises from the spin swapping effect at the Mn3Sn/permalloy interface.
NATURE COMMUNICATIONS
(2023)
Article
Multidisciplinary Sciences
Yu Zhang, Hongjun Xu, Ke Jia, Guibin Lan, Zhiheng Huang, Bin He, Congli He, Qiming Shao, Yizhan Wang, Mingkun Zhao, Tianyi Ma, Jing Dong, Chenyang Guo, Chen Cheng, Jiafeng Feng, Caihua Wan, Hongxiang Wei, Youguo Shi, Guangyu Zhang, Xiufeng Han, Guoqiang Yu
Summary: Spin-orbit torque (SOT) is a promising strategy to switch perpendicular magnetization without an external magnetic field, and using low-symmetry materials to generate SOT at room temperature is of great importance.
Article
Materials Science, Multidisciplinary
Liang Liu, Guowei Zhou, Xinyu Shu, Changjian Li, Weinan Lin, Lizhu Ren, Chenghang Zhou, Tieyang Zhao, Rui Guo, Qidong Xie, Han Wang, Jing Zhou, Ping Yang, Stephen J. Pennycook, Xiaohong Xu, Jingsheng Chen
Summary: In this study, the current-induced spin-orbit torque phenomenon in an all-oxide bilayer was investigated, and reversible switching of LSMO magnetization by electrical current was discovered. The results show that different directions of spin-orbit torque switching can be achieved by controlling the magnetic anisotropy. These findings may stimulate further development in spin-orbit torque studies in all-oxide systems.
Article
Physics, Multidisciplinary
Shutaro Karube, Takahiro Tanaka, Daichi Sugawara, Naohiro Kadoguchi, Makoto Kohda, Junsaku Nitta
Summary: The study investigates the generation of spin-splitter torque in collinear antiferromagnetic RuO2, revealing different spin current polarizations on various crystal planes. By utilizing this spin-splitter torque, field-free switching of ferromagnetic materials can be achieved, contributing to the development of antiferromagnetic spin-orbitronics.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
H. Bai, L. Han, X. Y. Feng, Y. J. Zhou, R. X. Su, Q. Wang, L. Y. Liao, W. X. Zhu, X. Z. Chen, F. Pan, X. L. Fan, C. Song
Summary: This article provides experimental evidence of the spin splitting torque (SST) in collinear antiferromagnet RuO2 films, which combines the advantages of conventional spin transfer torque (STT) and spin-orbit torque (SOT) and enables controllable spin polarization. The findings not only expand the research field of spin torques but also propose the potential of RuO2 as a spin source.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Applied
Bharat Grover, Binoy Krishna Hazra, Tianping Ma, Banabir Pal, Nirel Bernstein, Amit Rothschild, Abhay Kant Srivastava, Samiran Choudhury, Georg Woltersdorf, Amir Capua, Stuart S. P. Parkin
Summary: In this study, the dependence of the spin Hall angle θSH was investigated in epitaxial Al2O3/Pt, MgO/Pt films using a spin-torque driven ferromagnetic resonance method. It was found that the electrical technique had limitations in accurately quantifying θSH at high current densities and could result in erroneous values, particularly for films with large inhomogeneous broadening. The study also revealed a strong dependence of θSH on the crystallographic direction.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Thomas Scheike, Qingyi Xiang, Zhenchao Wen, Hiroaki Sukegawa, Tadakatsu Ohkubo, Kazuhiro Hono, Seiji Mitani
Summary: Giant tunnel magnetoresistance (TMR) ratios were achieved in epitaxial Fe/MgO/Fe(001) exchange-biased spin-valve magnetic tunnel junctions by tuning growth conditions for each layer and growing on a highly (001)-oriented Cr buffer layer. Specific features include symmetric differential conductance spectra and plateau-like deep local minima in dI/dV.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Multidisciplinary
Cong Xiao, Weikang Wu, Hui Wang, Yue-Xin Huang, Xiaolong Feng, Huiying Liu, Guang-Yu Guo, Qian Niu, Shengyuan A. Yang
Summary: We propose a method for generating spin in second order of electric fields that is time-reversal-even and dominates spin polarization in a wide range of nonmagnetic materials with centrosymmetry. This method also leads to a novel nonlinear spin-orbit torque in magnets. We demonstrate the quantum origin of this effect from the momentum space dipole of the anomalous spin polarizability. First-principles calculations predict sizable spin generation in several nonmagnetic hcp metals, monolayer TiTe2, and ferromagnetic monolayer MnSe2, which can be experimentally detected. Our work opens up new possibilities for nonlinear spintronics in both nonmagnetic and magnetic systems.
PHYSICAL REVIEW LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Robin T. K. Schock, Jonathan Neuwald, Wolfgang Moeckel, Matthias Kronseder, Luka Pirker, Maja Remskar, Andreas K. K. Huettel
Summary: It is demonstrated that adding a bismuth semimetal layer between the contact metal and the nanomaterial significantly improves the properties of the contacts, leading to better stability and less trap states.
ADVANCED MATERIALS
(2023)
Article
Physics, Multidisciplinary
L. Chen, S. Mankovsky, M. Kronseder, D. Schuh, M. Prager, D. Bougeard, H. Ebert, D. Weiss, C. H. Back
Summary: Tuning of anisotropic Gilbert damping Delta alpha has been achieved in ultrathin single-crystalline Fe films on GaAs (001). A nonmonotonic dependence of Delta alpha on film thickness t is observed, with an increase for 16 ML > t > 8.5 ML and a decrease for 8.5 ML > t > 6.5 ML accompanied by a sign reversal at t = 6.5 ML. First-principle calculations capture the sign reversal, indicating a change in the anisotropic density of states. The t(-1) dependence of anisotropic damping suggests the emergence of an anisotropic effective spin mixing conductance according to spin pumping theory.
PHYSICAL REVIEW LETTERS
(2023)
Review
Physics, Multidisciplinary
M. Kuepferling, A. Casiraghi, G. Soares, G. Durin, F. Garcia-Sanchez, L. Chen, C. H. Back, C. H. Marrows, S. Tacchi, G. Carlotti
Summary: This review examines the state of the art measurement techniques for the Dzyaloshinskii-Moriya interaction constant (DMI constant D), particularly in systems where the DMI arises from the interface between two materials. The review provides an overview of experimental techniques, theoretical background, and models for quantifying the DMI constant. The measurement techniques are categorized into three types: domain-wall-based measurements, spin-wave-based measurements, and spin-orbit torque-based measurements. The advantages and disadvantages of each method are analyzed, and the D values at different interfaces are compared. The review aims to improve understanding of the applicability of different techniques and explain discrepancies in literature values.
REVIEWS OF MODERN PHYSICS
(2023)
Article
Multidisciplinary Sciences
B. G. Markus, M. Gmitra, B. Dora, G. Csosz, T. Feher, P. Szirmai, B. Nafradi, V. Zolyomi, L. Forro, J. Fabian, F. Simon
Summary: Graphite's electron spins dynamics presents an unexpected behavior, with the longitudinal (T-1) and transverse (T-2) relaxation times being markedly different. Injected spins with perpendicular polarization have an extraordinarily long lifetime of 100 ns at room temperature, ten times longer than the best graphene samples. This suggests that thin films of graphite or multilayer AB graphene stacks can be excellent platforms for spintronics applications compatible with 2D van der Waals technologies.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Karol Szalowski, Marko Milivojevic, Denis Kochan, Martin Gmitra
Summary: Proximity-induced fine features and spin-textures of the electronic bands in graphene-based van der Waals heterostructures can be explored by tailoring the twist angle. The emergence of charge density wave (CDW) in 1T-TaS2 significantly enhances Rashba spin-orbit splitting in graphene and tilts the spin texture. Moreover, the CDW phase leads to the spontaneous emergence of in-plane magnetic order and the exchange coupling proximity effect between 1T-TaS2 and graphene.
Article
Chemistry, Physical
M. Rothe, G. Quintard, M. Kronseder, P. Bauduin, T. Zemb, W. Kunz
Summary: This study investigates the microstructure of H[C8E5c] and its metal salts using X-ray scattering methods, which shows the existence of spherical micelles in diluted aqueous solutions and the interdigitation of head groups at high concentrations. The study also reveals the arrangement of metal cations between the micelles, which could be responsible for the unique properties of these systems.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
Correction
Chemistry, Physical
Iaroslav Lutsyk, Karol Szalowski, Pawel Krukowski, Pawel Dabrowski, Maciej Rogala, Witold Kozlowski, Maxime Le Ster, Michal Piskorski, Dorota A. Kowalczyk, Wojciech Rys, Rafal Dunal, Aleksandra Nadolska, Klaudia Toczek, Przemyslaw Przybysz, Ewa Lacinska, Johannes Binder, Andrzej Wysmolek, Natalia Olszowska, Jacek J. Kolodziej, Martin Gmitra, Takuma Hattori, Yuji Kuwahara, Guang Bian, Tai-Chang Chiang, Pawel J. Kowalczyk
Article
Chemistry, Physical
Iaroslav Lutsyk, Karoli Szalowski, Pawel Krukowski, Pawel Dabrowski, Maciej Rogala, Witold Kozlowski, Maxime Le Ster, Michal Piskorski, Dorota A. Kowalczyk, Wojciech Rys, Rafal Dunal, Aleksandra Nadolska, Klaudia Toczek, Przemyslaw Przybysz, Ewa Lacinska, Johannes Binder, Andrzej Wysmolek, Natalia Olszowska, Jacek J. Kolodziej, Martin Gmitra, Takuma Hattori, Yuji Kuwahara, Guang Bian, Tai-Chang Chiang, Pawel J. Kowalczyk
Summary: The influence of intrinsic defects of 1T-TaS2 on charge density waves (CDWs) was investigated using scanning tunneling microscopy and spectroscopy (STM, STS), angle-resolved photoelectron spectroscopy (ARPES), and density functional theory (DFT). Various structural defects were identified, most of which had a local character limited to a single CDW site. However, one exception acted as a dopant, leading to band-bending and affecting multiple neighboring sites. While only one type of defect could be observed by STM topographic imaging, all defects were easily resolved in STS mapping. The modulation of the Mott band gap commensurate with the CDW and breaking of the three-fold symmetry of electronic states were observed. DFT calculations were used to investigate the electronic structure, focusing on sulfur vacancy and oxygen-sulfur substitution. The sulfur vacancy system showed metallic behavior and was identified as the origin of one of the experimentally observed defects. Moreover, the oxidation of 1T-TaS2 had different effects depending on the substitution site, resulting in electronic property heterogeneity.
Article
Multidisciplinary Sciences
Juraj Krempasky, Gunther Springholz, Sunil Wilfred D'Souza, Ondrej Caha, Martin Gmitra, Andreas Ney, C. A. F. Vaz, Cinthia Piamonteze, Mauro Fanciulli, Dominik Kriegner, Jonas A. Krieger, Thomas Prokscha, Zaher Salman, Jan Minar, J. Hugo Dil
Summary: The interplay between spin-orbit interaction and magnetic order is actively studied in condensed matter physics. In this study, researchers report unique and unexpected observations in thin multiferroic Ge1-xMnxTe films, including the ability to switch the ferrimagnetic order with small currents and the coherent spread of magnetic order.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Thomas Naimer, Jaroslav Fabian
Summary: We investigate the proximity-induced spin-orbit coupling (SOC) in heterostructures of twisted graphene and topological insulators (TIs) Bi2Se3 and Bi2Te3 from first principles. Straining graphene and applying a transverse electric field, we construct commensurate supercells and adjust resulting band offsets. The low energy electronic spectrum is then fitted to an effective Hamiltonian comprising orbital and spin-orbit terms. For twist angles 0 degrees ≤ θ ≤ 20 degrees, we find dominant spin-orbit couplings of the valley-Zeeman and Rashba types, both a few meV strong. We also observe a sign change in the induced valley-Zeeman SOC at θ = 0 ∼ 10 degrees. The resulting in-plane spin structure from the Rashba SOC acquires a nonzero radial component, except at θ = 0 degrees or 30 degrees. At θ = 30 degrees, the graphene Dirac cone directly interacts with the TI surface state. By exploring this twist angle in more detail, including gating, TI thicknesses, and lateral shifts, we confirm the emergence of the proximitized Kane-Mele SOC, with the possibility of sign change by electrically tuning the Dirac cone within the TI bulk band gap.
Article
Materials Science, Multidisciplinary
Alexis Wartelle, Franz Vilsmeier, Takuya Taniguchi, Christian H. Back
Summary: In this article, the concept of caustics in wave propagation is discussed, which refers to the envelope of a finite-extent wavefront. The presence of folds and cusps in a caustic results in enhanced wave amplitudes. The authors focus on a related phenomenon, caustic beams, which are well-defined beams that originate solely from the geometric properties of the corresponding dispersion relation. The existence of caustic beams has been observed in the case of phonons and the authors provide an overview of this effect in the context of spin waves in ferromagnetic films.
Article
Materials Science, Multidisciplinary
M. Hild, L. E. Golub, A. Fuhrmann, M. Otteneder, M. Kronseder, M. Matsubara, T. Kobayashi, D. Oshima, A. Honda, T. Kato, J. Wunderlich, C. Back, S. D. Ganichev
Summary: We report on spin ratchet currents driven by terahertz radiation electric fields in a Co/Pt magnetic metamaterial formed by triangle-shaped holes. The radiation causes a polarization-independent spin-polarized ratchet current by inducing periodic asymmetric radiation intensity distribution and a phase-shifted periodic asymmetric electrostatic force. The magnetization of the Co/Pt film results in a spin ratchet current caused by both the anomalous Hall and the anomalous Nernst effects, as well as a polarization-dependent trigonal spin photocurrent.
Article
Materials Science, Multidisciplinary
M. Vogel, B. Zimmermann, J. Wild, F. Schwarzhuber, C. Mewes, T. Mewes, J. Zweck, C. H. Back
Summary: Thermally induced spin dynamics in solids have attracted broad interest for fundamental physics and spintronic applications. By using high-resolution Lorentz transmission electron microscopy, this study investigates the dynamics of magnetic vortex cores in thin ferromagnetic platelets driven by thermomagnonic torques. Large deflections of the magnetic vortex core transverse to the temperature gradient direction are observed. The results provide insights into the interplay of temperature and spin and pave the way for manipulating magnetic domains on the nanoscale.
Article
Materials Science, Multidisciplinary
Klaus Zollner, Paulo E. Faria Jr, Jaroslav Fabian
Summary: In this study, the twist-angle and gate dependence of the proximity-induced exchange coupling between monolayer transition-metal dichalcogenides (TMDCs) MoSe2 and WSe2 and the ferromagnetic semiconductor CrI3 was investigated using first-principles calculations. It was found that the valence band (VB) edge exchange splitting of TMDCs transitions from about -2 meV to 2 meV upon twisting, while the conduction band (CB) edge exchange splitting remains nearly unchanged at around -3 meV. The exchange coupling of the VB of WSe2 (MoSe2) on CrI3 changes sign at around 8 degrees (16 degrees). The results highlight the important impact of twist angle and gating in magnetic vdW heterostructures.
