Article
Nanoscience & Nanotechnology
Tianli Jin, Gerard Joseph Lim, Han Yin Poh, Shuo Wu, Funan Tan, Wen Siang Lew
Summary: This study proposes a technique to modulate the spin reflection and spin density of states within a heavy-metal Pt through interfacing with a dielectric MgO layer. The researchers demonstrate tunability of the effective out-of-plane spin torque acting on the ferromagnetic Co layer, enabling current-induced SOT magnetization switching without the assistance of an external magnetic field. The influence of the MgO layer thickness on effective SOT efficiency shows saturation at 4 nm, while up to 80% of field-free magnetization switching ratio is achieved with the MgO between 5 and 8 nm. By substituting the dielectric with Ti or Pt, the researchers confirm that the MgO layer is indeed responsible for the observed field-free magnetization switching mechanism.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Nanoscience & Nanotechnology
Ruiyue Chu, Bin Cui, Liang Liu, Weikang Liu, Tingting Miao, Xue Ren, Bin Cheng, Xiangxiang Zhao, Xinyi Wu, Shuyun Wu, Jifan Hu
Summary: Reversible and non-volatile control of critical current and spin Hall efficiency was achieved in TaN/W/Pt/Co/Pt/TaN heterostructures through ionic liquid gating-induced hydrogen ion adsorption and desorption. Thinning of Pt and TaN capping layers enabled oxygen ion migration towards the Co layer, resulting in exchange bias field and field-free magnetization switching for Boolean logic operation.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Materials Science, Multidisciplinary
Gyu Won Kim, Do Duc Cuong, Yong Jin Kim, In Ho Cha, Taehyun Kim, Min Hyeok Lee, OukJae Lee, Hionsuck Baik, Soon Cheol Hong, Sonny H. Rhim, Young Keun Kim
Summary: The study introduces W-Ta and W-V alloy layers to enhance spin-orbit torque efficiency, with experimental results confirming a 40% improvement in SOT switching efficiency with W-V alloy. Through a combination of theory and experiment, an optimized heterostructure is found to boost torque-based switching efficiency by 40%.
NPG ASIA MATERIALS
(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
Physics, Applied
Xiaoyu Feng, Jiguang Yao, Yongwei Cui, Peng Zhang, Qiaoning Bai, Li Xi, Jiangwei Cao, Desheng Xue, Xiaolong Fan
Summary: Exposure of a Co/Pt bilayer to air leads to trace oxidation at the Co/Pt interface, resulting in CoOx appearance causing negative spin Hall magnetoresistance and unconventional spin-orbit torques (SOTs). Considering CoOx as an individual magnetic layer between Pt and Co with perpendicular magnetization to Co and increasing spin transparency with temperature, helps in understanding spin transport characteristics at the interface and indicates that trace oxidation can effectively control SOT in magnetic heterostructures.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Yunzhuo Wu, Xiaoxue Zeng, Yonghai Guo, Qi Jia, Bo Wang, Jiangwei Cao
Summary: The study investigated spin-orbit torque (SOT) effect and magnetization switching in Pt/Co-Tb/Ta structures with various Co-Tb compositions. Results revealed a certain law for current-induced SOT effective fields in the structure, as well as low coercivity near the compensation composition enabling current-induced magnetization switching at a low threshold current density. Direct Kerr imaging verified two different current-induced switching mechanisms in the Pt/Co-Tb/Ta system.
APPLIED PHYSICS LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Grayson Dao Hwee Wong, Zhan Xu, Weiliang Gan, Calvin Ching Ian Ang, Wai Cheung Law, Jiaxuan Tang, Wen Zhang, Ping Kwan Johnny Wong, Xiaojiang Yu, Feng Xu, Andrew T. S. Wee, Chim Seng Seet, Wen Siang Lew
Summary: Research has shown a significant increase in spin Hall efficiency in a Pt/Co bilayer when mechanical strain is applied, mainly due to a bulk effect in the Pt layer. Even after removing the strain, 78% of the enhancement effect is preserved, providing important insights for future utilization of mechanical strain in energy-efficient devices.
Article
Physics, Applied
Yonghai Guo, Yunzhuo Wu, Yang Cao, Xiaoxue Zeng, Bo Wang, Dezheng Yang, Xiaolong Fan, Jiangwei Cao
Summary: This study reports the current-induced deterministic field-free magnetization switching of the perpendicular Tb-Co ferrimagnet layer in a Co/Ti/Tb-Co trilayers, where the switching proportion and polarity of the Tb-Co ferrimagnet depend on the magnetization direction of the in-plane Co layer. The research confirms the current-induced field-free switching of the Tb-Co layer, demonstrating the potential for applications in SOT memory devices.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Hiroyuki Moriya, Akira Musha, Kazuya Ando
Summary: Efficient interfacial spin-orbit coupling in a Co/Pt bilayer can be manipulated by inserting a thin TiN layer, allowing for the dominance of interfacial contribution in the generation of spin-orbit torques. This result provides important information for developing efficient spin-orbitronic devices based on interfacial spin-orbit coupling.
APPLIED PHYSICS EXPRESS
(2021)
Article
Nanoscience & Nanotechnology
Maksim E. Stebliy, Alexander G. Kolesnikov, Michail A. Bazrov, Michail E. Letushev, Alexey Ognev, Aleksandr Davydenko, Ekaterina Stebliy, Aleksei G. Kozlov, Xiao Wang, Caihua Wan, Chi Fang, Mingkun Zhao, Xiufeng Han, Alexander S. Samardak
Summary: The experimental study investigates the effect of electric current on the exchange bias field in the Pt/Co/NiO structure, attributing the changes mainly to heating effects and the low Neel temperature. The injection of spin current and Joule heating contribute to the repeated variations in H-EB field value.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Materials Science, Multidisciplinary
Birui Wu, Menghao Jin, Ziji Shao, Haodong Fan, Jiahong Wen, Hai Li, Changqiu Yu, Bo Liu, Tiejun Zhou
Summary: This study investigates current-induced magnetization switching and dampinglike field in Pt/Co/PtMn trilayer films with a wedged ultrathin antiferromagnetic (AFM) PtMn layer. By breaking the symmetry with the effective shape anisotropy in the wedged AFM PtMn layer, field-free SOT switching is observed. The study finds that the dampinglike field is boosted by up to 30% through wedging the AFM PtMn layer, and the canting of spins caused by the wedge shape accounts for the observed field-free switching and enhancement of SOT efficiency.
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
Materials Science, Multidisciplinary
Utkarsh Shashank, Yoji Nakamura, Yu Kusaba, Takafumi Tomoda, Razia Nongjai, Asokan Kandasami, Rohit Medwal, Rajdeep Singh Rawat, Hironori Asada, Surbhi Gupta, Yasuhiro Fukuma
Summary: Recent studies have shown that incorporating nonmetallic lighter elements into 5d transition metals can enhance the efficiency of dampinglike torque. This finding is important for the development of low-power and robust magnetic memory.
Article
Chemistry, Multidisciplinary
David Cespedes-Berrocal, Heloise Damas, Sebastien Petit-Watelot, Davide Maccariello, Ping Tang, Aldo Arriola-Cordova, Pierre Vallobra, Yong Xu, Jean-Lois Bello, Elodie Martin, Sylvie Migot, Jaafar Ghanbaja, Shufeng Zhang, Michel Hehn, Stephane Mangin, Christos Panagopoulos, Vincent Cros, Albert Fert, Juan-Carlos Rojas-Sanchez
Summary: Spintronics utilizes spin-orbit coupling to produce spin currents and torques, often using heavy metals with large SOC. A new material architecture is introduced, demonstrating strong current-induced torques on ferrimagnetic layers due to Gd 5d states and interface engineering. This platform offers new opportunities for self-torquing single magnetic layers and generating spin currents.
ADVANCED MATERIALS
(2021)
Article
Physics, Applied
Jing Dong, Chen Cheng, Jinwu Wei, Hongjun Xu, Yu Zhang, Yuqiang Wang, Zengwei Zhu, Liang Li, Hao Wu, Guoqiang Yu, Xiufeng Han
Summary: This work focuses on the enhancement of damping-like and field-like spin-orbit torque (SOT) efficiencies and interfacial spin transparency (T-in) in the Py/NiO/Pt heterostructure. The SOT efficiencies and T-in are characterized using the spin-torque ferromagnetic resonance (ST-FMR) and spin-pumping (SP) techniques. By extracting and subtracting the inverse spin Hall voltage contamination induced by SP, accurate SOT efficiencies and T-in are obtained. The results show that the NiO insertion layer thickness affects the damping-like and field-like SOT efficiencies, indicating the importance of T-in. The maximum T-in reaches 0.82 for a 0.6 nm-thick NiO layer. This work highlights the effectiveness of NiO insertion in enhancing T-in and SOT efficiency.
APPLIED PHYSICS LETTERS
(2023)
Article
Nanoscience & Nanotechnology
Cheng-Wei Peng, Wei-Bang Liao, Tian-Yue Chen, Chi-Feng Pai
Summary: Recent research shows that amorphous WTe2 heterostructures deposited by magnetron sputtering exhibit high SOT efficiency and low damping constant, allowing for extremely low critical switching current density. The SOT efficiency is found to depend on the relative compositions of W and Te in the co-sputtered samples.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Nanoscience & Nanotechnology
Minh-Hai Nguyen, Chi-Feng Pai
Summary: Spin current and spin torque generation through spin-orbit interactions in solids, of bulk or interfacial origin, is central to spintronics research. The development of spin-orbit torque (SOT) driven magnetic dynamics and switching in diverse magnetic heterostructures paves the way for novel SOT memory and logic devices. Accurate and efficient SOT quantification techniques are crucial in understanding the role of SOTs in heterostructures.
Article
Physics, Applied
Yan-Ting Liu, Chao-Chung Huang, Kuan-Hao Chen, Yu-Hao Huang, Chia-Chin Tsai, Ting-Yu Chang, Chi-Feng Pai
Summary: The research investigates the type-x spin-orbit-torque (SOT) switching scheme for achieving lower power consumption, higher density, and better performance in SOT MRAM compared to conventional designs. Through systematic examination of type-x switching properties, key factors influencing the performance are identified, providing valuable insights for designing next-generation SOT MRAM.
PHYSICAL REVIEW APPLIED
(2021)
Article
Materials Science, Multidisciplinary
M. X. Guo, C. K. Cheng, Y. C. Liu, C. N. Wu, W. N. Chen, T. Y. Chen, C. T. Wu, C. H. Hsu, S. Q. Zhou, C. F. Chang, L. H. Tjeng, S. F. Lee, C. F. Pai, M. Hong, J. Kwo
Summary: In this study, single-crystal EuIG thin films were successfully grown on GGG substrates using epitaxial growth method, and exhibited strain-induced perpendicular magnetic anisotropy. By adjusting the sputtering conditions, the composition ratios of Eu/Fe in the films were varied to control the film strains. The films had smooth, particle-free surface with excellent crystallinity and a stable interface connection.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Physics, Applied
Yan-Ting Liu, Yu-Hao Huang, Chao-Chung Huang, Yung-Cheng Li, Chih-Lin Cheng, Chi-Feng Pai
Summary: This article demonstrates a simple measurement method to probe -x spin-orbit-torque (SOT) switching by observing current-driven differential planar Hall signals. The experimental results show that a canted magnetic easy axis engineered by field-annealing processes can generate robust field-free switching effects and further reduce the critical switching current density.
PHYSICAL REVIEW APPLIED
(2022)
Article
Physics, Applied
Yu-Hao Huang, Chao-Chung Huang, Wei-Bang Liao, Tian-Yue Chen, Chi-Feng Pai
Summary: This study reports on the interlayer DMI between two orthogonally magnetized ferromagnetic layers mediated by a Pt layer, demonstrating the chiral nature of the observed effective field of up to 37 Oe. The results show the potential of interlayer DMI to facilitate deterministic field-free switching in spin-memory applications.
PHYSICAL REVIEW APPLIED
(2022)
Article
Physics, Applied
Yung-Cheng Li, Yu-Hao Huang, Chao-Chung Huang, Yan-Ting Liu, Chi-Feng Pai
Summary: The investigation focuses on the interlayer Dzyaloshinskii-Moriya interaction (IDMI) in a Pt/Co multilayer system. It confirms the dominant role of IDMI in the current-induced field-free switching behavior through comparisons between layers with perpendicular magnetic anisotropy (PMA) and in-plane magnetic anisotropy (IMA).
PHYSICAL REVIEW APPLIED
(2023)
Article
Materials Science, Multidisciplinary
Wei-Bang Liao, Chun-Yi Lin, Tung-Yue Cheng, Chao-Chung Huang, Tian-Yue Chen, Chi-Feng Pai
Summary: This study systematically investigates the impact of processing on magnetic and spin-orbit torque (SOT) properties across a range of device sizes. It is observed that reducing the device size increases coercivity (Hc) and critical switching current density (J(sw)), while SOT efficiency (xi(DL)) remains independent of size. The current-driven hysteresis loop-shift measurement and domain-wall depinning model provide consistent estimates of J(sw). Comparing results from different devices, a consistent estimated dampinglike SOT efficiency can be reached.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Engineering, Electrical & Electronic
Yu-Fang Chiu, Yu-Fang Chiu, Chia-Chin Tsai, Chien-Min Lee, Ming-Yuan Song, Shy-Jay Lin, Xinyu Bao, Chi-Feng Pai
Summary: In this work, a BEOL-compatible CoFeB/MgO-based heterostructure with appropriate interfacial engineering strategies for spin???orbit torque magnetic random-access memories (SOT-MRAMs) is demonstrated. The thermally robust perpendicular magnetic anisotropy (PMA) and large damping-like spin???orbit torque (DL-SOT) efficiencies are achieved by using a Pt???Cr alloy as the spin current source (SCS) and inserting a Pt/Co/Pt composite layer for texture decoupling and ferromagnetic coupling. Additionally, the current-to-effective field conversion ratio is enhanced and the critical switching current density is reduced without compromising the thermal stability of the annealed heterostructure. These findings provide a viable pathway to integrate Pt-based SCSs with large ??DL into a BEOL-compatible platform for future SOT-MRAM devices with PMA.
ACS APPLIED ELECTRONIC MATERIALS
(2023)
Article
Physics, Multidisciplinary
Chao-Chung Huang, Chia-Chin Tsai, Wei-Bang Liao, Tian-Yue Chen, Chi-Feng Pai
Summary: This study demonstrates the characterization of spin-orbit torque (SOT) on magnetic heterostructures with perpendicular anisotropy using a deep learning-based vector magnet. The accuracy of the vector magnet's magnetic field calibration is achieved through deep learning models. The results obtained from the deep learning-trained vector magnet system are consistent with those obtained from a conventional setup, validating the reliability of the SOT characterization on the heterostructures.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Materials Science, Multidisciplinary
Ting-Yu Chang, Chih-Lin Cheng, Chao-Chung Huang, Cheng-Wei Peng, Yu-Hao Huang, Tian-Yue Chen, Yan-Ting Liu, Chi-Feng Pai
Summary: In W/CoFeB metallic bilayer heterostructures, a large unidirectional magnetoresistance (UMR) ratio of approximately 0.36% is observed at room temperature. Three different regimes are identified in terms of the current dependence of the UMR ratio, and a direct correlation between the large UMR and the transfer of spin angular momentum from the W layer to the CoFeB layer is verified through experiments. The large spin transfer torque (STT) UMR is found to stem from the tilting of magnetization affected by the spin Hall effect-induced STTs, and an alternative approach for estimating dampinglike spin torque efficiencies from magnetic heterostructures is proposed.
