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
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
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
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
Ziqi Zhou, Paul Marcon, Xavier Devaux, Philippe Pigeat, Alexandre Bouche, Sylvie Migot, Abdallah Jaafar, Remi Arras, Michel Vergnat, Lei Ren, Hans Tornatzky, Cedric Robert, Xavier Marie, Jean-Marie George, Henri-Yves Jaffres, Mathieu Stoffel, Herve Rinnert, Zhongming Wei, Pierre Renucci, Lionel Calmels, Yuan Lu
Summary: The study successfully demonstrated the growth of structures with large perpendicular magnetic anisotropy on monolayer molybdenum disulfide by inserting MgO to prevent the diffusion of ferromagnetic atoms. The thickness of MgO was found to modify the band structure of MoS2, showcasing potential for developing room temperature spin optoelectronic devices based on 2D transition-metal dichalcogenide materials.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Chemistry, Physical
Fengxuan Han, Wei Du, Mengli Liu, Hua Su, Huaiwu Zhang, Bo Liu, Hao Meng, Xiaoli Tang
Summary: The Pt/Ta seed layer has been shown to enhance the thermal stability of PMA by providing efficient diffusion paths for Ta and increasing Fe-O bonding to improve PMA and its temperature stability compared to a Ta single seed layer.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Physics, Applied
S. Tacchi, F. Casoli, M. G. Pini, A. Rettori, M. Madami, J. Akerman, T. T. Le, Q. N. Pham, H. L. Pham, T. N. Anh Nguyen
Summary: Utilizing alternating gradient force magnetometry and Brillouin light scattering experiments, this study investigated perpendicular magnetic anisotropy localized at the CoFeB-MgO interface in different heterostructures. Thermal treatment was found to significantly increase the PMA, and analysis of spin wave frequencies allowed estimation of the thickness dependence of PMA in a single CoFeB film. Additionally, the study of magnetic tunnel junctions revealed an antiferromagnetic interlayer exchange coupling between CoFeB layers that increased after annealing.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
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)
Article
Engineering, Electrical & Electronic
Tomohiro Ichinose, Tatsuya Yamamoto, Takayuki Nozaki, Kay Yakushiji, Shingo Tamaru, Makoto Konoto, Shinji Yuasa
Summary: We developed a cryogenic temperature deposition process for high-performance CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) on φ300 mm thermally oxidized silicon wafers. The effect of deposition temperature on CoFeB layers and its impact on nanostructure, magnetic, and magneto-transport properties of MTJs were investigated. Cryogenic deposition of CoFeB at 100 K resulted in enhancements of perpendicular magnetic anisotropy (PMA) and voltage-controlled magnetic anisotropy (VCMA) of the MTJs compared to room temperature deposition. Improved interfacial qualities at the MgO/CoFeB interfaces were observed with cryogenic temperature deposition.
ACS APPLIED ELECTRONIC MATERIALS
(2023)
Article
Chemistry, Physical
Young Chan Won, Sang Ho Lim
Summary: The study investigates the perpendicular magnetic anisotropy and crystalline structure of Ta/NiFeB/MgO stacks. Annealing induces PMA and increases magnetic moment, with the thinnest 0.5-nm Ta layer showing the strongest PMA at 400 degrees Celsius. X-ray diffraction confirms the formation of NiFe (001) phase essential for high tunneling magnetoresistance ratio.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Physical
Wei Du, Mengli Liu, Guocai Wang, Hua Su, Bo Liu, Hao Meng, Xiaoli Tang
Summary: This research investigates the properties of Pt/CoFeB/MgO (bottom structure) and MgO/CoFeB/Pt (top structure) samples with different compositions. It is found that the bottom structure always exhibits stronger perpendicular magnetic anisotropy (PMA) properties compared to the top structure. Additionally, a higher Co atomic composition in CoFeB leads to a stronger PMA. The results are attributed to the Pt-Co hybridization and the catalytic action of Pt on the Fe-O hybridization at the CoFeB/MgO interface.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Nanoscience & Nanotechnology
Qi Liu, Pengfei Liu, Xiaowen Li, Sixia Hu, Yuanmin Zhu, Cai Jin, Wenqiao Han, Yanjiang Ji, Zedong Xu, Songbai Hu, Mao Ye, Lang Chen
Summary: By designing and fabricating manganite-based magnetic tunnel junctions, we achieved perpendicular tunneling and observed spin-dependent tunneling behavior. The dominant role of direct tunneling was observed in the low bias region, while it was associated with thermionic emission in the high bias region.
ACS APPLIED MATERIALS & INTERFACES
(2022)
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
Nanoscience & Nanotechnology
Sicong Jiang, Safdar Nazir, Kesong Yang
Summary: This study presents a high-throughput screening approach to find candidate Heusler/MgO material interfaces for spintronic applications. By utilizing open quantum material repositories and conducting large-scale ab initio calculations, the researchers identified five full-Heusler compounds and two half-Heusler compounds as promising candidates for designing p-MTJs.
ACS APPLIED MATERIALS & INTERFACES
(2022)
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
Engineering, Electrical & Electronic
Yi-Chien Weng, Chih-Wei Cheng, G. Chern
IEEE TRANSACTIONS ON MAGNETICS
(2013)
Article
Engineering, Electrical & Electronic
Chih-Wei Cheng, Tsung-I Cheng, C. H. Shiue, Chih-Li Weng, Yan-Chr Tsai, G. Chern
IEEE TRANSACTIONS ON MAGNETICS
(2013)
Article
Engineering, Electrical & Electronic
C. C. Tsai, Chih-Wei Cheng, Meng-Chiau Tsai, G. Chern
IEEE TRANSACTIONS ON MAGNETICS
(2014)
Article
Engineering, Electrical & Electronic
Der-Sheng Lee, Hao-Ting Chang, Chih-Wei Cheng, Gung Chern
IEEE TRANSACTIONS ON MAGNETICS
(2014)
Article
Physics, Applied
Tsung-I Cheng, Chih-Wei Cheng, G. Chern
JOURNAL OF APPLIED PHYSICS
(2012)
Article
Physics, Applied
Wuwei Feng, Nai-Yuan Jiang, Shin-Da Huang, Hung-Ming Chen, Chih-Wei Cheng, G. Chern, Chin-Chung Yu
JOURNAL OF APPLIED PHYSICS
(2012)
Article
Physics, Applied
K. Kuo, C. W. Cheng, G. Chern
JOURNAL OF APPLIED PHYSICS
(2012)
Article
Physics, Applied
Meng-Chiau Tsai, Chih-Wei Cheng, C. C. Tsai, G. Chern
JOURNAL OF APPLIED PHYSICS
(2013)
Article
Physics, Applied
Y. S. Chen, Chih-Wei Cheng, G. Chern, J. G. Lin
JOURNAL OF APPLIED PHYSICS
(2014)
Article
Physics, Applied
C. C. Tsai, Chih-Wei Cheng, Yi-Chien Weng, G. Chern
JOURNAL OF APPLIED PHYSICS
(2014)
Article
Engineering, Electrical & Electronic
Shin-Huang Shen, Der-Sheng Lee, Chih-Wei Cheng, Wei-Jen Chan, G. Chern
IEEE TRANSACTIONS ON MAGNETICS
(2019)
Article
Physics, Applied
Kuan-Ming Chen, Chih-Wei Cheng, Jeng-Hua Wei, Yu-Chen Hsin, Yuan-Chieh Tseng
APPLIED PHYSICS LETTERS
(2020)
Article
Chemistry, Multidisciplinary
Yu-Han Huang, Chao-Yao Yang, Chih-Wei Cheng, Albert Lee, Chih-Hsiang Tseng, Hao Wu, Quanjun Pan, Xiaoyu Che, Chih-Huang Lai, Kang-Lang Wang, Hong-Ji Lin, Yuan-Chieh Tseng
Summary: In this study, an interesting spin-orbit torque ratchet involving the exchange spring effect in an IrMn/CoFeB bilayer device with perpendicular anisotropy and exchange bias is developed. The results show that the exchange spring in the IrMn/CoFeB bilayer yields unidirectional anisotropy, resulting in a collinear/orthogonal AFM/FM spin configuration at the interface. The ratcheting characteristics resulting from unidirectional anisotropy manifest in SOT switching, making it potentially useful in neuromorphic and memory applications.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Physics, Applied
Chih-Wei Cheng, Kuan-Ming Chen, Jeng-Hua Wei, Yu-Chen Hsin, Shyh-Shyuan Sheu, Chih- Wu, Yuan-Chieh Tseng
Summary: This study investigates the impact of magneto-static stray field interactions in miniaturized CoFeB/MgO magnetic tunnel junctions (MTJs) and compares the performance of the pillar and step structures. The results show that the stray field interactions have less influence on step MTJs compared to pillar MTJs during miniaturization. The findings are consistent with experimental results and are further supported by incorporating additional interactions in the free-layer of the structures. The study also highlights the importance of considering etching damage effects for accurate thermal stability simulations.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Physics, Applied
Akhil K. Ramesh, Chih-Wei Cheng, Ting-Chia Ku, Vaibhav Rana, Pratisha Gangwar, Pushparaj Singh, Yuan-Chieh Tseng
Summary: This paper presents an approach to investigate the switching performance of spin transfer torque MRAM devices using an interface imperfection model. The study reveals the inverse relationship between switching time and interface imperfection. It also proposes a model that considers the roughness parameter in analyzing the damping of CoFeB/MgO films.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
