Article
Materials Science, Multidisciplinary
Qixun Guo, Zhongxu Ren, He Bai, Xuemin Wang, Guanghua Yu, Wei He, Jiao Teng, Tao Zhu
Summary: The study experimentally investigated the perpendicular magnetic anisotropy properties of CoFeB/MgO films on 3d light-metal vanadium. It observed a sign change of effective torque fields with the increase of vanadium thickness, indicating a competition of multiple effects on current-induced torques in the weakly spin-orbit coupled V/CoFeB/MgO multilayers. These findings have implications for the fundamental understanding of current-induced torque and further device applications using 3d light transition-metal based heterostructures.
Article
Physics, Applied
Grayson Dao Hwee Wong, Calvin Ching Ian Ang, Weiliang Gan, Wai Cheung Law, Zhan Xu, Feng Xu, Chim Seng Seet, Wen Siang Lew
Summary: The study proposes a method to achieve reversible modulation of spin-orbit torque and Gilbert damping parameter through mechanical strain and mild annealing. Experimental results show that the device's functionality can be tuned using these methods, and its robustness is demonstrated in endurance tests.
APPLIED PHYSICS LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Seungmo Yang, Tae-Seong Ju, Changsoo Kim, Hyun-Joong Kim, Kyongmo An, Kyoung-Woong Moon, Sungkyun Park, Chanyong Hwang
Summary: This study presents a method for creating magnetic skyrmions in typical perpendicular magnetic anisotropy films and determines the magnitude of the required external magnetic fields. Additionally, the study explores the dependence of the minimum size of skyrmions on the magnetic anisotropy.
Article
Physics, Applied
Haihong Yin, Xiangyu Zheng, Junlin Wang, Yu Zhou, Balati Kuerbanjiang, Guanqi Li, Xianyang Lu, Kaiyu Tong, Yichuan Wang, Jing Wu, Vlado K. Lazarov, Richard F. L. Evans, Roy W. Chantrell, Jianwang Cai, Bo Liu, Hao Meng, Yongbing Xu
Summary: The study reveals that Skyrmions are more likely to form in samples with higher amounts of structural defects, and the density of Skyrmions can be controlled by artificial tuning of the defect amount. By utilizing first-order reversal curves, the stable region and density of Skyrmions can be efficiently controlled in return magnetization loops.
APPLIED PHYSICS LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Jinwu Wei, Xiao Wang, Baoshan Cui, Chenyang Guo, Hongjun Xu, Yao Guang, Yuqiang Wang, Xuming Luo, Caihua Wan, Jiafeng Feng, Hongxiang Wei, Gen Yin, Xiufeng Han, Guoqiang Yu
Summary: Synthetic antiferromagnets (SAFs) show potential in next-generation spintronic devices due to zero net magnetization and high thermal stability, despite typically requiring an in-plane effective magnetic field. A new study demonstrates field-free switching in an all-SAF system with significantly reduced net magnetization, showing robustness up to approximately 460 K.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Physics, Applied
B. Ravi Kumar, Sreekar Guddeti, P. S. Anil Kumar
Summary: The magnetic field driven domain-wall motion in out-of-plane magnetized Ta/Pt/CoFeB/Pt multilayers, both as-deposited and annealed, was investigated using Kerr microscopy. The study focused on the modified interfacial Dzyaloshinskii-Moriya interaction (iDMI) that controls the dynamics of chiral domain walls. The strength of iDMI was found to decrease with increasing CoFeB thickness and annealing temperature, which can be attributed to changes in the interface properties and annealing-induced effects.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
M. Hassan, S. Laureti, C. Rinaldi, F. Fagiani, S. Varotto, G. Barucca, N. Y. Schmidt, G. Varvaro, M. Albrecht
Summary: Flexible magneto-resistive heterostructures with perpendicular magnetic anisotropy have not been studied extensively, despite the potential for additional functionality and improved performance. This study successfully prepared flexible PMA Co/Pd-based GMR spin-valve stacks using an innovative transfer-and-bonding strategy, overcoming limitations associated with direct deposition on polymer substrates. The resulting flexible spin-valves exhibit a sizeable GMR ratio and high robustness against bending, allowing for integration on curved surfaces and the development of advanced devices based on flexible magneto-resistive structures with perpendicular magnetic anisotropy.
NANOSCALE ADVANCES
(2021)
Article
Physics, Applied
Sang Sun Lee, Tae-Seong Ju, Hee-Sung Han, Mi-Young Im, Changsoo Kim, Kyoung-Woong Moon, Seungmo Yang
Summary: In this study, we investigated the effect of atomic-scale interface engineering by inserting a Ta layer between the CoFeB/MgO interface on perpendicular magnetic anisotropy, saturation magnetization, and Dzyaloshinskii-Moriya interaction. Our findings contribute to the development of optimized CoFeB-based skyrmion hosting materials.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
Zhuoyi Li, Xianyang Lu, Zhe Zhang, Wenjia Li, TaoTao Li, Jian Zhou, Yu Yan, Ruobai Liu, Jun Du, Ronghua Liu, Xinran Wang, Yao Li, Liang He, Jing Wu, Rong Zhang, Yongbing Xu
Summary: This study conducted a comprehensive investigation on improving the spin-orbit torque (SOT) efficiency of the Ta/CoFeB structure by inserting an oxide insulating layer Fe2O3. It was found that a thickness of only 1-5 nm of Fe2O3 significantly reduced the SOT critical switching current by 70% and enhanced the spin Hall angle of Ta. Both types of spin-orbit torques, damping-like and field-like torques, were significantly enhanced. The observed enhanced SOT efficiency was attributed to the atomic diffusion of O from the Fe2O3 underlayer, leading to the partial oxidization of the Ta layer and the Ta/CoFeB interfaces. The results provide a reliable method to improve the SOT performance in perpendicularly magnetized structures for potential real-world applications in spintronic devices.
APPLIED PHYSICS LETTERS
(2023)
Article
Nanoscience & Nanotechnology
Lizhu Ren, Liang Liu, Xinyu Shu, Weinan Lin, Ping Yang, Jingsheng Chen, Kie Leong Teo
Summary: The experimental demonstration of current-induced spin-orbit torque (SOT) magnetization switching in a ferrimagnetic D0(22)-Mn3Ge film with high bulk PMA and thermal stability suggests it as a promising candidate for high-density SOT magnetic random-access memory devices. The large effective damping-like SOT efficiency and magnetization switching can be explained by the double-spin source layers and negative-exchange interaction of the ferrimagnet.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Materials Science, Multidisciplinary
S. K. Syamlal, Hari Prasanth Perumal, Jaivardhan Sinha
Summary: The study investigates the magnetization reversal mechanism in perpendicularly magnetized nanodots under the influence of Dzyaloshinskii-Moriya Interaction (DMI) using micromagnetic simulation. Results show that an increase in DMI strength leads to a decrease in coercive field and the chirality induced nucleation of magnetization reversal from the oblique side edges.
Article
Physics, Multidisciplinary
Xing Chen, Cuixiu Zheng, Yu Zhang, Sai Zhou, Yaowen Liu, Zongzhi Zhang
Summary: The investigation of magnetic excitations in interlayer exchange-coupled synthetic antiferromagnets with perpendicular magnetic anisotropy reveals new spin wave and polarization modes, as well as dynamic properties under bias magnetic fields. These findings provide fundamental insight into the potential spintronic applications of these materials.
NEW JOURNAL OF PHYSICS
(2021)
Article
Chemistry, Multidisciplinary
Lizhu Ren, Chenghang Zhou, Xiaohe Song, Herng Tun Seng, Liang Liu, Chaojiang Li, Tieyang Zhao, Zhenyi Zheng, Jun Ding, Yuan Ping Feng, Jingsheng Chen, Kie Leong Teo
Summary: Electrically manipulating magnetic moments by spin-orbit torque (SOT) has potential applications in magnetic memories and logic devices. In this study, highly textured, polycrystalline Heusler alloy MnxPtyGe (MPG) films were found to exhibit reversible switching of magnetization with low switching current density. Additionally, MPG shows a memristive characteristic and the ability for deterministic field-free switching of magnetization.
Article
Physics, Multidisciplinary
Ying Cao, Zhicheng Xie, Zhiyuan Zhao, Yumin Yang, Na Lei, Bingfeng Miao, Dahai Wei
Summary: This paper investigates the performance of spin-orbit torque in heavy metal/ferromagnetic metal periodic multilayers. A series of perpendicular magnetized multilayers were successfully fabricated and the thickness of the Ni layer was varied to study the spin-orbit torque. The efficiency of the spin-orbit torque was found to be effectively modulated by the ratio of Pt and Ni in the multilayers.
Article
Physics, Applied
Masaaki Tanaka, Motoharu Furuta, Tomoyuki Ichikawa, Masaya Morishita, Yu-Min Hung, Syuta Honda, Teruo Ono, Ko Mibu
Summary: This study demonstrated the generation of perpendicularly spin-polarized electronic currents using a tunnel spin-filtering effect through insulative Fe-rich cobalt ferrite CoxFe3-xO4+delta (I-CFO) barriers with perpendicular magnetic anisotropy (PMA). The combination of well-controlled compositions and lattice strains in spinel-type C-CFO and I-CFO films is applicable as a spin-injection source for spintronics devices when perpendicularly spin-polarized electronic currents are required.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
H. Matsumoto, S. Ota, T. Koyama, D. Chiba
Summary: Reversible control of magnetic anisotropy has been demonstrated in Pt/Co and Pd/Co structures formed on a flexible substrate by biaxially stretching the substrate. The in-plane biaxial tensile strain leads to significantly modulation of the perpendicular magnetic anisotropy, with the magnetic easy axis switching from in-plane to out-of-plane under up to 2% biaxial strain. In-plane magnetic anisotropy induced by biaxial tensile strain is also investigated in this study.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Takamasa Hirai, Hossein Sepehri-Amin, Kento Hasegawa, Tomohiro Koyama, Ryo Iguchi, Tadakatsu Ohkubo, Daichi Chiba, Ken-ichi Uchida
Summary: The study demonstrates the uniaxial-strain-induced switching between cooling and heating using an Ni thin film on an organic flexible substrate, showcasing the potential for versatile thermal management based on spin caloritronics. By observing the reversible sign reversal of the temperature modulation induced by the anisotropic magneto-Peltier effect, the research provides insights for future developments in active thermal control systems.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
A. Obinata, T. Koyama, F. Matsukura, K. Nakamura, D. Chiba
Summary: This study investigates the effect of electric fields on magnetic moments in perpendicularly magnetized Co ultra-thin films on a Pt underlayer. The results show that the change in magnetic moment per electrically increased electron depends on the thickness of the Co film, with values approaching -1 mu (B)/electron for thicker Co films and exceeding +1 mu (B)/electron for thinner Co films. The band structures suggest that intermixing between Co and Pt contributes to the deviation from the Slater-Pauling curve in systems with extremely small Co thickness.
APPLIED PHYSICS LETTERS
(2021)
Article
Multidisciplinary Sciences
Shinya Ota, Pham Van Thach, Hiroyuki Awano, Akira Ando, Kentaro Toyoki, Yoshinori Kotani, Tetsuya Nakamura, Tomohiro Koyama, Daichi Chiba
Summary: The study reveals that the compensation temperature of ferrimagnetic Tb-Fe films on a flexible substrate is significantly affected by tensile strain, resulting in a reduction of magnetic moments of both Fe and Tb. Analyzed using molecular field theory, the changes in exchange coupling between Fe and Tb atoms are speculated to be the cause of this phenomenon.
SCIENTIFIC REPORTS
(2021)
Article
Physics, Applied
Hiroki Matsumoto, Shinya Ota, Tomohiro Koyama, Daichi Chiba
Summary: Researchers have fabricated a spin valve structure with a Pd/Co-based film and demonstrated a controllable spin reorientation transition by applying strain, resulting in a drastic change in the magnetoresistance curve.
APPLIED PHYSICS EXPRESS
(2022)
Article
Physics, Applied
K. Saito, A. Imai, S. Ota, T. Koyama, A. Ando, D. Chiba
Summary: This study demonstrates the considerable potential of a CoFeB/MgO-based magnetic tunnel junction (MTJ) directly formed on a flexible substrate as a high-sensitivity strain gauge. Under the condition of external magnetic-field assistance, the flexible MTJ achieves a gauge factor of approximately 1000, which is the highest sensitivity reported for a film-type strain gauge and about 500 times larger than that of the most prevalent metal-foil strain gauge. Moreover, using a flexible MTJ with strain-insensitive and strain-sensitive layers, a large resistance change due to strain application can be achieved even without the presence of a magnetic field.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Kento Hasegawa, Tomohiro Koyama, Daichi Chiba
Summary: By introducing lateral structural asymmetry through gate-induced redox reactions, current-induced switching of perpendicular magnetization without any external magnetic field was demonstrated. The essential role of structural asymmetry was confirmed when the gate electrode covered only half of the wire. The origin of the perpendicular effective field was identified to be the Oersted field at the wire edges rather than the Rashba effect.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
T. Koyama, Y. Nakatani, D. Chiba
Summary: In this study, a Pt/Co/MgO system with regions exhibiting different anisotropy was artificially created to investigate the chirality-induced EMF at the PM/IM boundary. The EMF in the IM region was probed using magnetoresistance measurements, revealing that it predominantly acts on the magnetization near the PM/IM boundary. The sign and magnitude of the observed EMF suggest that it is caused by iDMI in the present system.
APPLIED PHYSICS LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Yoshiharu Goshima, Shinsuke Kashiwagi, Takahiro Namazu
Summary: This paper describes a Raman spectroscopic study to evaluate the impact of vacuum annealing on the surface modification of a focused ion beam (FIB) induced damaged layer on a single crystalline silicon substrate. It was found that vacuum annealing can partially recover the damaged layer. The comparison between phase fractions and mechanical properties provides insights into the annealing effect.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B
(2023)
Article
Engineering, Electrical & Electronic
Hiromichi Ando, Takahiro Namazu
Summary: The influence of vacuum annealing on the mechanical characteristics of silicon nanowires fabricated using focused ion beam technologies was investigated. The study found that annealing can improve the mechanical properties of submicrometer-sized silicon nanowires, but has little effect on nano-sized silicon nanowires. Tensile strength was found to increase with increasing nanowire size.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B
(2023)
Article
Materials Science, Multidisciplinary
Takamasa Hirai, Kento Hasegawa, Shinya Ota, Motohiro Suzuki, Tomohiro Koyama, Daichi Chiba
Summary: In Co/Pt/oxide systems, fieldlike SOT is significantly influenced by the adjacent oxide material, while dampinglike SOT is almost irrelevant to oxides. The efficiency of FL SOT in the Pt/HfO2 sample is 2.2 times greater than that in the Pt/MgO sample at the maximum. X-ray magnetic circular dichroism spectroscopy suggests that the modulation of the electronic structure at the Pt/oxide interface contributes to SOT enhancement.
Article
Materials Science, Multidisciplinary
K. Hasegawa, T. Koyama, D. Chiba
Summary: The study found that inserting a thin Cu interlayer into the Pt/Co interface can enhance USMR, where the Cu/Co system exhibits a large GMR. Experimental results show that the spin current injection into the Co layer is not modulated by the Cu interlayer, and USMR increases with Cu thickness, reaching a peak before decreasing.
