Article
Materials Science, Multidisciplinary
Yue Hu, Shiming Yan, Shiran Gao, Chengyang Zhao, Wen Qiao, Ru Bai, Tiejun Zhou
Summary: In this paper, the magnetic anisotropy constant Ki and voltage-controlled magnetic anisotropy coefficient VCMA of MgO/PtMnAs heterostructures with two different interfacial configurations are studied using first-principles calculations. It is found that MgO/AsMn_Pt heterostructure has a larger Ki and higher VCMA. The origin of these behaviors is analyzed by orbital-resolved magnetic anisotropy energy.
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
(2023)
Article
Computer Science, Information Systems
Gulafshan Gulafshan, Selma Amara, Rajat Kumar, Danial Khan, Hossein Fariborzi, Yehia Massoud
Summary: Today's technology requires devices that are compact, portable, fast, and energy-efficient. This paper presents a circuit design based on voltage-controlled magnetic anisotropy magnetoresistive random access memory (VCMA-MRAM), which utilizes logic-in-memory computing paradigm and approximate computation to address the memory bottleneck issues in the present computing system. Simulation results demonstrate that the proposed circuit's approximate adder consumes about 300% less energy and is 2.3 times faster than its exact counterpart.
Article
Engineering, Electrical & Electronic
Robert Carpenter, Woojin Kim, Kiroubanand Sankaran, Mohamed Ben Chroud, Maxwel Gama Monteiro, Johan Swerts, Gouri Sankar Kar, Sebastien Couet
Summary: One of the key challenges in the industrialisation of VCMA-MRAM is the reliability of the writing process. This study demonstrates a simple method for controlling mu H-0(off) by varying the Co concentration and number of repeats in the Co/Pt HL, resulting in a FL offset of mu H-0(off) =0mT with minimal impact on other device properties. Furthermore, the optimised device shows a symmetric switching probability distribution with respect to VCMA pulse width.
IEEE TRANSACTIONS ON NANOTECHNOLOGY
(2023)
Article
Nanoscience & Nanotechnology
K. Li, J. Feng, X. Yuan, L. Gan, Z. Lu, R. Xiong
Summary: A new writing scheme with a unidirectional pulse current is proposed for STT-MRAM. It can achieve the switching of magnetization in bilayered nano-pillars and optimize the dimensions and magnetic parameters for lower switching current density and shorter switching time. The scheme has great potential for the application of materials with high spin polarization and can avoid the injection of writing current into the junction.
Article
Multidisciplinary Sciences
Andrea Meo, Jessada Chureemart, Roy W. Chantrell, Phanwadee Chureemart
Summary: We present a theoretical investigation of the magnetisation reversal process in CoFeB-based magnetic tunnel junctions. Our results reveal that the combination of spin orbit torque and spin transfer torque can assist in achieving efficient and fast magnetisation reversal on the sub-nanosecond timescale.
SCIENTIFIC REPORTS
(2022)
Review
Materials Science, Multidisciplinary
Viola Krizakova, Manu Perumkunnil, Sebastien Couet, Pietro Gambardella, Kevin Garello
Summary: Spin-orbit torques (SOT) provide a versatile tool for manipulating magnetization and have applications in spintronic memory and computing. This paper reviews the characteristics of SOT and its use in magnetic tunnel junction (MTJ) devices.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Engineering, Electrical & Electronic
Bi Wu, Haonan Zhu, Ke Chen, Chenggang Yan, Weiqiang Liu
Summary: Conventional computing architectures based on the von Neumann structure are facing the problem of the 'memory wall' due to the mismatch between memory and processor. The concept of logic in-memory (LiM) is proposed as a solution to reduce data migration overhead, and it has been extensively studied in various memory technologies. Among them, SOT-MRAM stands out as a promising candidate due to its advantages of non-volatility, low power consumption, high speed, and high density. This paper proposes in-memory logic operations based on US SOT-MRAM devices, which can be performed with minimal modifications to peripheral circuits and optimized to minimize performance degradation caused by device instability.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS
(2023)
Article
Chemistry, Physical
Qizhong Zhao, Fanghua Tian, Tieyan Chang, Kaiyan Cao, Dingchen Wang, Yin Zhang, Chao Zhou, Xiaoqin Ke, Wenliang Zuo, Yu Wang, Sen Yang, Xiaoping Song
Summary: In this study, the magnetization reversal phenomenon in the Ni20Mn3B6 alloy was investigated at low applied fields, revealing two compensation temperatures. The first temperature is attributed to competition between Mn atoms at different positions, while the second arises from moment rotation to satisfy Zeeman energy. This phenomenon enables tunable switching of magnetization between positive and negative values, providing potential applications in spintronic devices and magnetic storage materials.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Optics
Shihan Gao, Runji Cai, Wanjie Xiong, Chudong Xu
Summary: This article investigates the influence of damping on helicity-independent all-optical switching (HI-AOS) through simulation using a semiclassical atomic spin dynamics model. The results show that smaller damping can affect the switching process and slow down the rate of magnetization dynamics. This study provides a theoretical foundation for exploring the optimization parameters of HI-AOS.
Article
Chemistry, Inorganic & Nuclear
Xiaoxuan Ma, Ning Yuan, Wanting Yang, Shuang Zhu, Chenfei Shi, Huan Song, Zhiqiang Sun, Baojuan Kang, Wei Ren, Shixun Cao
Summary: In this study, the field-tuning mechanisms of spill switching and spin reorientation (SR) transition in PrxEr1-xFeO3 crystals were investigated. It was found that the type and temperature region of SR transition can be tuned by introducing different ratios of Pr3+ doping. External field can also regulate the trigger temperature of spin switching in Pr0.3Er0.7FeO3 crystals.
INORGANIC CHEMISTRY
(2022)
Article
Multidisciplinary Sciences
L. Aviles-Felix, L. Farcis, Z. Jin, L. Alvaro-Gomez, G. Li, K. T. Yamada, A. Kirilyuk, A. V. Kimel, Th. Rasing, B. Dieny, R. C. Sousa, I. L. Prejbeanu, L. D. Buda-Prejbeanu
Summary: This study uses atomistic spin simulations to investigate all-optical switching in multilayered structures. By calculating the thermal variation and magnetization dynamics, it explores the possibility of thermally-induced magnetization switching in Tb/Co multilayers under specific conditions.
SCIENTIFIC REPORTS
(2021)
Article
Engineering, Electrical & Electronic
Pankaj Pathak, Dhiman Mallick
Summary: This study reports the self-biased, in-plane 180 degrees magnetization switching of FeGaB nanomagnets on PMN-PT piezoelectric substrate, achieved by varying the thickness of nanomagnets with different aspect ratio. The research also reveals that in-plane 180 degrees magnetization switching for larger aspect ratio nanomagnets is limited due to the maximum achievable stress from the piezoelectric layer. The underlying physics, including the relationship between the critical switching time and energy, is elucidated using finite difference method (FDM) micromagnetic model coupled with elastodynamic and electrostatic conditions.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Chemistry, Physical
I-Hsuan Kao, Ryan Muzzio, Hantao Zhang, Menglin Zhu, Jacob Gobbo, Sean Yuan, Daniel Weber, Rahul Rao, Jiahan Li, James H. Edgar, Joshua E. Goldberger, Jiaqiang Yan, David G. Mandrus, Jinwoo Hwang, Ran Cheng, Jyoti Katoch, Simranjeet Singh
Summary: This paper demonstrates the experimental realization of field-free deterministic magnetic switching using the out-of-plane antidamping spin-orbit torque in the quantum material WTe2, and confirms this phenomenon through numerical simulations. This is of great importance for next-generation spintronic applications.
Article
Physics, Applied
Keisuke Yamada, Shun-ichi Takamatsu, Hiroki Asakawa, Yoshinobu Nakatani
Summary: This study reports current-induced magnetization switching in a perpendicularly magnetized nanomagnet under specific conditions and investigates the influencing factors. The results demonstrate that the magnetization switching can be reduced under certain conditions, which is of great significance for exploring the characteristics of nanomagnets.
APPLIED PHYSICS EXPRESS
(2023)
Article
Multidisciplinary Sciences
Fen Xue, Shy-Jay Lin, Mingyuan Song, William Hwang, Christoph Klewe, Chien-Min Lee, Emrah Turgut, Padraic Shafer, Arturas Vailionis, Yen-Lin Huang, Wilman Tsai, Xinyu Bao, Shan X. X. Wang
Summary: Xue et al. investigate 'type-x' spin-orbit torque switching in Platinum/Cobalt multilayers, demonstrating unique spin polarizations and field-free magnetization switching. The unconventional spin currents result from the strong orbital magnetic moment observed in the low-dimensional Co films. Their work provides additional pathways for electrical control of spintronic devices in pursuit of high-speed, high-density, and low-energy non-volatile memory.
NATURE COMMUNICATIONS
(2023)
Correction
Materials Science, Multidisciplinary
Hiroshi Imamura, Hiroko Arai, Rie Matsumoto
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Physics, Applied
Daiju Hayashi, Yoichi Shiota, Mio Ishibashi, Ryusuke Hisatomi, Takahiro Moriyama, Teruo Ono
Summary: We investigated the coherently excited propagating magnons in in-plane magnetized synthetic antiferromagnets using heterodyne-magnetooptical Kerr effect technique. Under an in-plane magnetic field at a 45-degree angle away from the magnon propagation direction, we observed mode splitting of the magnon dispersion relation due to magnon-magnon coupling between acoustic and optical magnon modes. Strong coupling with a cooperativity of 8.4 +/- 1.3 was achieved for finite wavenumber. These results provide a deep understanding of the properties of coherently excited magnons in synthetic antiferromagnets, which will be helpful for designing advanced magnonic devices.
APPLIED PHYSICS EXPRESS
(2023)
Article
Physics, Applied
Atsushi Sugihara, Tomohiro Ichinose, Shingo Tamaru, Tatsuya Yamamoto, Makoto Konoto, Takayuki Nozaki, Shinji Yuasa
Summary: We deposited a 1.1 nm ultrathin CoFeB layer as the storage layer for MgO-based magnetic tunnel junctions in spin-transfer-torque (STT) magnetoresistive random-access memory (MRAM) on phi 300 mm wafers at 100 K, and investigated its effect on the magnetization dynamics of CoFeB. The results show that deposition at cryogenic temperatures is an effective manufacturing process for high-quality magnetic thin films with low magnetic damping, achieved through the improvement in the interfacial quality.
APPLIED PHYSICS EXPRESS
(2023)
Article
Physics, Applied
Yuta Kobayashi, Yoichi Shiota, Hideki Narita, Teruo Ono, Takahiro Moriyama
Summary: The study reveals that the Joule heating induced by voltage pulses can cause a magnetic phase transition in D0(19)-Mn3Sn, altering the energy landscape relevant to spin-orbit torque switching. This poses challenges in accurately determining the thermal stability factor and highlights the importance of cautious estimation.
APPLIED PHYSICS LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Hiroko Arai, Hiroshi Imamura
Summary: Voltage controlled magnetoresistive random access memory (VC MRAM) is a promising candidate for future low-power high-density memory. The two main causes of bit errors in VC MRAM are write error and retention error. As the size of the memory cell decreases, the data retention time decreases, resulting in a transition from the write-error-dominant region to the retention-error-dominant region. The characteristic time of this transition is analyzed in relation to the effective anisotropy constant, K-0.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Yukie Kitaoka, Hiroshi Imamura
Summary: Recent research has shown that the perpendicular magnetic anisotropy (PMA) of magnetoresistive random access memory (MRAM) can be significantly enhanced by inserting an ultrathin LiF layer at an Fe/MgO interface. First-principles calculations revealed that the PMA enhancement is mainly due to the suppression of Fe and O atom mixing at the interface. Additionally, in-plane Fe-F coupling contributes positively to the magnetocrystalline anisotropy energy (MAE), while Fe-O coupling has a negative contribution. These findings are valuable for the design of high-PMA materials.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Physics, Multidisciplinary
Toshiki Yamaji, Hiroshi Imamura
Summary: High-speed magnetization switching of nanomagnets is crucial for faster information processing. The study explores a potential method called ballistic switching using pulsed magnetic fields. By designing material parameters, such as anisotropy constant, saturation magnetization, and Gilbert damping constant, the researchers found that increasing the magnetic anisotropy constant or decreasing the saturation magnetization can reduce the pulse width required for ballistic switching. They also discovered an optimal value of the Gilbert damping constant that minimizes the pulse width needed.
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
(2023)
Article
Chemistry, Multidisciplinary
Hiroyasu Nakayama, Takayuki Nozaki, Tomohiro Nozaki, Shinji Yuasa
Summary: The voltage-controlled magnetic anisotropy (VCMA) effect in ferromagnets is important for next-generation magnetic memory technologies. This study proposes a pathway to tune the VCMA effect by inserting heavy metals and using different underlayers. The effects of different underlayer materials on the VCMA coefficient suggest the electron depletion from underlayers.
ADVANCED MATERIALS INTERFACES
(2023)
Article
Physics, Applied
Tatsuya Yamamoto, Tomohiro Ichinose, Jun Uzuhashi, Takayuki Nozaki, Tadakatsu Ohkubo, Kay Yakushiji, Shingo Tamaru, Shinji Yuasa
Summary: The magnetic and electrical transport properties of magnetic tunnel junctions (MTJs) consisting of a Co75Mn25/Mo/Co20Fe60B20 multilayer were studied. By optimizing the Co75Mn25 layer thickness and annealing temperature, the Co75Mn25/Mo/Co20Fe60B20 multilayer sandwiched between two MgO layers exhibits remarkable perpendicular magnetic anisotropy with a uniaxial magnetic anisotropy constant as large as 0.2 MJ/m3. The current-in-plane tunneling measurement reveals a large tunneling magnetoresistance of over 100% in perpendicularly magnetized MTJs. These experimental results indicate the applicability of Co75Mn25 alloy for magnetic random access memory devices.
PHYSICAL REVIEW APPLIED
(2023)
Article
Physics, Applied
S. Funada, Y. Ishikawa, M. Kimata, K. Hayashi, T. Sano, K. Sugi, Y. Fujii, S. Mitsudo, Y. Shiota, T. Ono, T. Moriyama
Summary: In this study, we demonstrate the electrical detection of antiferromagnetic dynamics in ferrimagnetic Gd-Co thin films using a 154-GHz gyrotron. The captured resonant modes allow us to characterize the peculiar magnetization dynamics in Gd-Co. This milestone towards THz measurements for antiferro-and ferrimagnetic thin films has important implications.
PHYSICAL REVIEW APPLIED
(2023)
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
Nanoscience & Nanotechnology
Maksim E. Stebliy, Michail A. Bazrov, Zhimba Zh. Namsaraev, Michail E. Letushev, Aleksei G. Kozlov, Valerii A. Antonov, Ekaterina Stebliy, Aleksandr Davydenko, Alexey Ognev, Yoichi Shiota, Teruo Ono, Alexander S. Samardak
Summary: Nano- and microstructures based on ferrimagnets can achieve efficient magnetization switching and stable spin textures. In this study, we experimentally demonstrate the local realization of compensation state using nonuniform Joule heating. By applying current pulses, it is possible to induce spin-orbit torques in opposite directions, resulting in local magnetization switching. These findings provide an alternative approach for engineering advanced ferrimagnetic nanodevices.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Nanoscience & Nanotechnology
Takayuki Nozaki, Tomohiro Ichinose, Jun Uzuhashi, Tatsuya Yamamoto, Makoto Konoto, Kay Yakushiji, Tadakatsu Ohkubo, Shinji Yuasa
Summary: This study investigates the influence of the buffer material and cryogenic temperature deposition process on the voltage-controlled magnetic anisotropy (VCMA) effect in CoFeB layers in MgO-based magnetic tunnel junctions. The use of TaB buffers allows for a flat and less-contaminated CoFeB/MgO interface while cryogenic temperature deposition enhances the efficiency of the VCMA effect and its annealing tolerance. Introduction of interface engineering methods leads to a large VCMA coefficient.
