Article
Chemistry, Multidisciplinary
Leonid A. Shelukhin, Rashid R. Gareev, Vladyslav Zbarsky, Jakob Walowski, Markus Munzenberg, Nikolay A. Pertsev, Alexandra M. Kalashnikova
Summary: This study presents an experimental investigation of laser-induced magnetization dynamics in a CoFeB/MgO/CoFeB MTJ. The results show that a femtosecond laser pulse can induce magnetization precession in the thinner CoFeB layer and the precession frequency increases nonlinearly with increasing pump fluence. Additionally, the gradual quenching of interfacial magnetic anisotropy with increasing fluence is explained by laser-induced heating of the MTJ.
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
Physics, Applied
Zhiqiang Cao, Weibin Chen, Shiyang Lu, Shaohua Yan, Yu Zhang, Zitong Zhou, Yaodi Yang, Zhi Li, Weisheng Zhao, Qunwen Leng
Summary: This paper introduces a double-interface CoFeB/MgO p-TMR structure to improve thermal stability of MTJ-based devices, and investigates the performance of TMR film stacks by varying the thickness of the MgO cap layer. It is found that decreasing the MgO cap layer thickness enhances sensitivity and linear output of the sensing layer.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Tatsuya Yamamoto, Tomohiro Ichinose, Jun Uzuhashi, Takayuki Nozaki, Tadakatsu Ohkubo, Kay Yakushiji, Shingo Tamaru, Hitoshi Kubota, Akio Fukushima, Kazuhiro Hono, Shinji Yuasa
Summary: In this study, we investigate the perpendicular magnetic anisotropy (PMA) in MgO/CoFeB (CFB)/MgO junctions by introducing an angstrom-thick Mo spacer layer. It is found that perpendicularly magnetized CFB/Mo/CFB films can be obtained for a wide range of CFB thicknesses, achieving a large PMA energy density. The voltage-controlled magnetic anisotropy effect shows a sign inversion between the 'top free' and 'bottom free' magnetic tunnel junctions, indicating the importance of the flatness of the CFB/MgO interface for improving the efficiency of the effect.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Physics, Applied
Kaihua Lou, Tunan Xie, Qianwen Zhao, Baiqing Jiang, ChaoChao Xia, Hanying Zhang, Zhihong Yao, Chong Bi, Chong Bi
Summary: This study reports the reliable establishment of perpendicular magnetic anisotropy (PMA) in CoFeB/MgO films on various buffer layers without the need for post-annealing. Precise control of MgO thickness is found to be critical for achieving the as-deposited PMA, which is not significantly influenced by post-annealing. Instead, post-annealing enhances unsaturated PMA by modulating oxygen distributions, rather than crystallinity or Co- and Fe-O bonding. These findings provide a practical approach to construct spin-orbitronic devices based on various high-efficient SOT materials.
APPLIED PHYSICS LETTERS
(2022)
Article
Nanoscience & Nanotechnology
V. Bansal, J. -M. Tonnerre, E. Mossang, L. Ortega, F. Fettar, J. Chatterjee, S. Auffret, I. -L. Prejbeanu, B. Dieny
Summary: In this study, we used soft X-ray resonant magnetic reflectivity to investigate the magnetization profile of a CoFeB/MgO sample. The results showed a gradient distribution of magnetization for both Fe and Co at the interfaces, indicating a stable property of the sample.
Article
Physics, Applied
Q. X. Guo, K. Wang, H. Bai, Z. C. Zheng, L. H. Wang, X. M. Wang, W. He, G. H. Yu, J. Teng, T. Zhu
Summary: In this study, the realization of PMA in a W buffered CoFeB/MgO stack is achieved by inserting a thin Zr dusting layer between the CoFeB and MgO layers. An ultra-high thermal stability of PMA in the W/CoFeB/Zr/MgO stack is observed, making it a potential candidate for practical applications of spin-logic devices compatible with mature CMOS integrated techniques.
APPLIED PHYSICS LETTERS
(2022)
Article
Multidisciplinary Sciences
Ana S. Silva, Simao P. Sa, Sergey A. Bunyaev, Carlos Garcia, Inigo J. Sola, Gleb N. Kakazei, Helder Crespo, David Navas
Summary: The dynamical properties of CoFeB/Pd multilayered ultrathin films were studied, revealing a maximum perpendicular magnetic anisotropy at a CoFeB thickness of 3 angstrom. An in-plane orientation of magnetization occurred when the CoFeB layer thickness exceeded 5 angstrom.
SCIENTIFIC REPORTS
(2021)
Article
Materials Science, Multidisciplinary
Tatsuya Yamamoto, Takayuki Nozaki, Kay Yakushiji, Shingo Tamaru, Hitoshi Kubota, Akio Fukushima, Shinji Yuasa
Summary: The study shows that Ta layer in MgO/Ta/CoFeB/MgO junctions can enhance the PMA of magnetic films and eliminate the diffusion of Ta, leading to superior thermal stability and the release of VCMA effect. In addition, the Co-Fe compositional variation in CoFeB layer associated with Ta insertion is related to the changes in PMA and VCMA.
Article
Physics, Applied
Jinsong Xu, C. L. Chien
Summary: This work demonstrates voltage-controlled spin-orbit torque (SOT) switching in W/CoFeB/MgO films with perpendicular magnetic anisotropy (PMA) by applying voltage through SrTiO3 with high dielectric constant. The study shows that a DC voltage can significantly decrease PMA by 45%, reduce switching current by 23%, and increase damping-like torque, essential characteristics for voltage-controlled and voltage-select SOT switching spintronic devices.
APPLIED PHYSICS LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Motoya Shinozaki, Junta Igarashi, Shuichi Iwakiri, Takahito Kitada, Keisuke Hayakawa, Butsurin Jinnai, Tomohiro Otsuka, Shunsuke Fukami, Kensuke Kobayashi, Hideo Ohno
Summary: Magnetic tunnel junctions (MTJs) with spin-dependent conductance were investigated in this study. The nonlinear conductance at low bias regime was evaluated in nanoscale MTJs. The relationships between different conductance components were examined. The results indicated that the conductance components were correlated with the junction size and external magnetic field. The findings provide insights into the electron transport mechanism in nanoscale MTJs.
Article
Materials Science, Multidisciplinary
Yanjie Wang, Xiaoyuan Nie, Junhui Song, Chao Wang, Fan Yang, Yaodan Chi, Xiaotian Yang, Ye Shen, Chunyan Xu
Summary: Using first-principles calculations, the diffusion process of B atoms and the origin of perpendicular magnetic anisotropy (PMA) in MgO|CoFe|Ta structures with boron were studied. It was observed that B atoms are more likely to enter the Ta layer than the FeCo and MgO layers, which is consistent with experimental and theoretical results. The physical origin of the interfacial PMA in the Ta|CoFe|MgO structure with B element was also elucidated and found to come from both the MgO|CoFe and CoFe|Ta layer interfaces. These findings provide a comprehensive understanding of PMA and suggest the potential for achieving high thermal stability in advanced-node STT-MRAM.
RESULTS IN PHYSICS
(2023)
Article
Nanoscience & Nanotechnology
Abhijeet Ranjan, Chun-Liang Yang, Chia-Chang Lee, Rudis Ismael Salinas Padilla, Chih-Huang Lai
Summary: Writing using spin-orbit torque (SOT) has been widely studied in the field of magnetic random-access memory (MRAM). This study introduces rhenium (Re) as a new material for achieving thermally stable perpendicular magnetic anisotropy (PMA) and spin-orbit torque (SOT) switching, providing a new avenue for the material design of SOT-based MRAM.
Article
Physics, Applied
Hua Lv, Joao Fidalgo, Thomas Kampfe, Juergen Langer, Jerzy Wrona, Berthold Ocker, Paulo P. Freitas, Susana Cardoso
Summary: This study systematically investigates the Seebeck effect in nano scale p-MTJs induced by Joule heating. Experimental results show a sign change of the thermovoltage between different magnetic states, indicating the significant dependence of the Seebeck effect on the magnetic state of the p-MTJ. The efficiency of energy re-use can be improved by optimizing the non-magnetic layers.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Engineering, Electrical & Electronic
K. Nishioka, S. Miura, H. Honjo, H. Naganuma, T. V. A. Nguyen, T. Watanabe, S. Ikeda, T. Endoh
Summary: The effect of magnetic coupling on the thermal stability factor Delta in magnetic tunnel junctions (MTJs) was investigated. It was found that increasing the energy constant J(cpl) of magnetic coupling can enhance Delta, but saturates when J(cpl) exceeds a critical value J(cpl_c). The magnetic static coupling constant J(stat) was much smaller than J(cpl_c), and an interlayer exchange coupling constant J(ex_c) is required to cover the difference between J(cpl_c) and J(stat). Experimental results were in good agreement with calculations, showing that Delta can be enhanced by adjusting the stiffness constant As.
IEEE TRANSACTIONS ON MAGNETICS
(2022)
