Article
Physics, Applied
Motoki Endo, Muftah Al-Mahdawi, Mikihiko Oogane, Yasuo Ando
Summary: This study demonstrates the control and design of sensitivity in magnetic tunnel junction (MTJ) sensors with a vortex-type sensing layer. By varying the pinned layer size, the sensitivity to magnetic field can be tuned linearly. The research provides a potential method for achieving multiple sensing functionalities from a single sensor.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Physics, Applied
Ronghuan Xie, Shun Wang, Li Cai, Xiaotian Cui, Senmiao Liu, Qiang Cao, Changwen Zhang, Qikun Huang, Shishen Yan
Summary: Bulk spin-orbit torque (SOT) driven memristive switching is achieved in perpendicularly magnetized CoPt alloy films by breaking the inversion symmetry using a composition gradient. Analog-like magnetization switching with multiple intermediate states can be obtained by applying current pulses with different amplitudes or repetition number. The programmable magnetization manipulation and controllable switching probability dependent on pulse frequency or repetition number emulate the weight update of synapses and the integrate-and-fire function of neurons, making it a promising candidate for SOT-based neuromorphic hardware.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Chikako Yoshida, Tomohiro Tanaka, Tadashi Ataka, Minoru Hoshina, Atsushi Furuya
Summary: This study investigates the magnetic field-free switching of a three-terminal perpendicular magnetic tunnel junction using spin-orbit torque and spin-transfer torque, driven by voltage-controlled magnetic anisotropy. By optimizing the voltage pulse configuration, high success rate of switching is achieved, with lower power consumption compared to STT-alone writing. Additionally, SOT-STT writing shows greater potential for practical use compared to external magnetic field-assisted SOT writing.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Zhuonan Lin, Iana Volvach, Vitaliy Lomakin
Summary: We propose an approach to minimize the critical current for magnetization switching in magnetic tunnel junctions by optimizing the spatial distribution of the current density. The critical current is determined by promoting the growth of one of the magnetization eigenstates over time. By overlapping the spatial distributions of the eigenstates and current density, the excitation of the eigenstates is enhanced. This optimization results in a significant reduction in the critical current and an increase in the switching efficiency.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Zilu Wang, Pingzhi Li, Mouad Fattouhi, Yuxuan Yao, Youri L. W. Van Hees, Casper F. Schippers, Xueying Zhang, Reinoud Lavrijsen, Felipe Garcia-Sanchez, Eduardo Martinez, Albert Fert, Weisheng Zhao, Bert Koopmans
Summary: Field-free spin-orbit torque (SOT) switching of perpendicular synthetic antiferromagnets (p-SAFs) is achieved through the introduction of an interlayer with Dzyaloshinskii-Moriya interactions (DMIs). The existence of the DMI interlayer is experimentally confirmed, and deterministic field-free switching is demonstrated. The proposed strategy is compatible with magnetic tunnel junction device structure and provides a method for high-performance SOT devices based on p-SAFs.
CELL REPORTS PHYSICAL SCIENCE
(2023)
Article
Physics, Condensed Matter
Long Liu, Sutao Sun, Yunchang Huo, Shuang Li, Tiwen Han
Summary: By investigating a hybrid four-terminal Josephson junction, we found that under specific conditions, a 4 pi-periodic current can be observed through the normal terminal, while a 2 pi-periodic current can be observed through the superconducting terminal.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2022)
Article
Chemistry, Multidisciplinary
Bin Fang, Luis Sanchez-Tejerina San Jose, Aitian Chen, Yan Li, Dongxing Zheng, Yinchang Ma, Hanin Algaidi, Kai Liu, Giovanni Finocchio, Xixiang Zhang
Summary: This research demonstrates the feasibility of achieving perpendicular EB reversal in antiferromagnetic materials and ferromagnetic multilayers, providing a direction for introducing new functionality in spintronic devices.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Vaishnavi Kateel, Viola Krizakova, Siddharth Rao, Kaiming Cai, Mohit Gupta, Maxwel Gama Monteiro, Farrukh Yasin, Bart Soree, Johan De Boeck, Sebastien Couet, Pietro Gambardella, Gouri Sankar Kar, Kevin Garello
Summary: Current-induced spin-orbit torques (SOTs) are used to manipulate the magnetic state of magnetic tunnel junctions (MTJs) for various applications. However, the need for an external magnetic field limits its practical implementation. In this study, a field-free switching solution is proposed by shaping the SOT channel to create a bend in the SOT current, enabling deterministic switching. Experimental results demonstrate the feasibility of this approach in nanosecond time scales.
Article
Chemistry, Multidisciplinary
Shipu Xu, Xing Xu, Shidang Xu
Summary: A charge-gradient-induced ferroelectricity, featured with the first order phase transition, is achieved by modulating the stoichiometric oxygen in the Bi2O2Se/Bi2Se3O9 bilayer. The ferroelectric tunnel junction based on this bilayer exhibits a comparable electroresistance of 100 and can switch repeatedly or retain its state for 360 seconds.
Article
Mechanics
Suresh Behara, Venu Chandra, N. R. Prashanth
Summary: This study numerically investigates the three-dimensional transition in the wake of two tandem co-rotating cylinders. The results show that the rotation of the cylinders and the change of the streamwise gaps both affect the transition modes and the characteristics of the near-wake flow.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Engineering, Electrical & Electronic
Elmer Monteblanco, Aurelie Solignac, Chloe Chopin, Julien Moulin, Pierre Belliot, Noemie Belin, Paolo Campiglio, Claude Fermon, Myriam Pannetier-Lecoeur
Summary: In this manuscript, a calculation method is proposed to model magneto-resistive elements as fluctuating resistances to correct the output voltage noise of magnetic tunnel junctions (MTJ) in standard electronic circuits. The method is validated on different circuit configurations, showing a correction factor that affects output voltage noise and sensitivity values. By combining the correction factor with normalization by the number of MTJ pillars and their surface area, this method allows for universal comparison of performance data from various literature sources.
IEEE SENSORS JOURNAL
(2021)
Article
Mechanics
S. J. Terrington, K. Hourigan, M. C. Thompson
Summary: This article presents a three-dimensional theory of vorticity creation on generalised interfaces, including both non-slip and free-slip boundaries. Vorticity can be created on a boundary by the inviscid relative acceleration between fluid elements on each side of the boundary, driven by either tangential pressure gradients or body forces. Viscosity acts to transfer circulation between the vortex sheet representing the slip velocity on the interface, and the fluid interior, but is not responsible for the creation of vorticity on the interface. This formulation also describes a principle of vorticity conservation for interfacial and free-surface flows.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Materials Science, Multidisciplinary
D. J. P. de Sousa, Fei Xue, J. P. Wang, P. M. Haney, Tony Low
Summary: In this study, we investigate the current-induced torques in asymmetric magnetic tunnel junctions with a conventional ferromagnet and a magnetic Weyl semimetal contact. By analyzing the chirality of the Weyl semimetal and its effects on the torques acting on the ferromagnet, we reveal the presence of large fieldlike torques on the magnetic Weyl semimetal that exceed conventional limits. Our results shed light on the new physics of multilayered spintronic devices utilizing magnetic Weyl semimetals, potentially leading to more energy-efficient spintronic devices.
Article
Materials Science, Multidisciplinary
Payal Bhattacharjee, Anjan Barman, Saswati Barman
Summary: This study explores the magnetic analog of the bipolar junction transistor using magnetic vortices as an alternative. Micromagnetic simulations are used to study the dynamics of magnetic vortices in physically separated nanodisks. A magnetic vortex transistor (MVT) is designed when the nanodisks are arranged in a triangular layout. The study demonstrates the possibility of tuning the MVT by varying the configuration, polarity combination, and changing the position of the input signal.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2022)
Article
Engineering, Electrical & Electronic
Wenlong Cai, Akash Kumar, Ao Du, Kewen Shi, Rui Xiao, Kaihua Cao, Jialiang Yin, Johan Akerman, Weisheng Zhao
Summary: Spintronic oscillators are promising candidates for neuromorphic computing due to their size, non-linearity, and synchronization properties. However, current-induced spin-transfer torque in spin torque nano-oscillators can result in high power consumption and reliability issues. Spin Hall nano-oscillators offer higher energy efficiency, but their limited power emission restricts their applications.
IEEE ELECTRON DEVICE LETTERS
(2023)
Article
Nanoscience & Nanotechnology
Mori Watanabe, Ryoya Nakamura, Sanghyun Lee, Takuya Asano, Takashi Ibe, Masashi Tokuda, Hiroki Taniguchi, Daichi Ueta, Yoshinori Okada, Kensuke Kobayashi, Yasuhiro Niimi
Summary: Magnetoresistance measurements in CeTe3 thin film devices revealed a significant interplay between magnetic ordering and conduction electrons, affecting the effective cyclotron mass and other properties of the material. Analysis of the temperature dependence of the oscillation amplitude provided insights into the material's characteristics in both paramagnetic and antiferromagnetic states.
Article
Physics, Multidisciplinary
Daiju Terasawa, Shota Norimoto, Tomonori Arakawa, Meydi Ferrier, Akira Fukuda, Kensuke Kobayashi, Yoshiro Hirayama
Summary: The study found that the conductance of a quantum point contact on a GaAs/AlGaAs double quantum well is significantly influenced by the magnetic field in the region, resulting in a 17.5 times enhancement of the g-factor due to Zeeman energy. This phenomenon is mainly attributed to the low electron density and high mobility in the strong many-body interaction region.
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
(2021)
Article
Instruments & Instrumentation
Sanghyun Lee, Masayuki Hashisaka, Takafumi Akiho, Kensuke Kobayashi, Koji Muraki
Summary: This study demonstrates the suitability of a homemade GaAs HEMT amplifier for current-noise measurements in mesoscopic devices at dilution-refrigerator temperatures. The lower noise characteristics of the homemade HEMT allow for a lower noise floor in the experimental setup and more efficient current-noise measurement compared to commercial HEMTs. The high resolution of the measurement setup is showcased by comparing it with a conventional one using a commercial HEMT.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2021)
Article
Nanoscience & Nanotechnology
Tomoharu Ohta, Masashi Tokuda, Shuichi Iwakiri, Kosuke Sakai, Benjamin Driesen, Yoshinori Okada, Kensuke Kobayashi, Yasuhiro Niimi
Summary: In this study, magnetoresistance measurements were conducted on van der Waals ferromagnetic devices using quenched and nonquenched Fe5GeTe2 crystals. A butterfly-shaped hysteresis in magnetoresistance was observed, with a large MR ratio attributed to magnetic fluctuations resulting from the complex magnetic structure in the material.
Article
Physics, Applied
Moeta Tsukamoto, Kensuke Ogawa, Hayato Ozawa, Takayuki Iwasaki, Mutsuko Hatano, Kento Sasaki, Kensuke Kobayashi
Summary: This study demonstrates vector magnetometry using perfectly aligned NV centers in diamond, and shows a method for performing three-dimensional vector measurement of magnetic fields generated by current flowing in nearby wires. The research shows that the sensitivity of our method in detecting magnetic fields is significantly higher, especially for time-varying magnetic signals.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Koji Fujiwara, Shuichi Iwakiri, Mori Watanabe, Ryoya Nakamura, Masahiko Yokoi, Kensuke Kobayashi, Yasuhiro Niimi
Summary: The study found that CDW transitions in NbSe3 devices exhibit good stability, with clear resistivity changes observed even in thinner devices. This suggests that surface acoustic waves could be useful for modulating CDW states in NbSe3 devices.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2021)
Article
Multidisciplinary Sciences
Tokuro Hata, Yoshimichi Teratani, Tomonori Arakawa, Sanghyun Lee, Meydi Ferrier, Richard Deblock, Rui Sakano, Akira Oguri, Kensuke Kobayashi
Summary: The researchers experimentally demonstrate the importance of three-body correlations in the nonlinear conductance of a Kondo-correlated quantum dot at finite magnetic field, validating the recent extension of the Fermi liquid theory into the non-equilibrium regime.
NATURE COMMUNICATIONS
(2021)
Review
Physics, Multidisciplinary
Jorge Puebla, Yunyoung Hwang, Kouta Kondou, Yoshichika Otani
Summary: This paper provides an overview of the progress in spin conversion and discusses the additional consequences beyond efficient spin conversion that arise from the formation of quasiparticles at band crossings.
ANNALEN DER PHYSIK
(2022)
Article
Chemistry, Multidisciplinary
Kouta Kondou, Masanobu Shiga, Shoya Sakamoto, Hiroyuki Inuzuka, Atsuko Nihonyanagi, Fumito Araoka, Masaki Kobayashi, Shinji Miwa, Daigo Miyajima, YoshiChika Otani
Summary: This study investigates chirality-induced current-in-plane magnetoresistance in a chiral molecule/ferromagnetic metal bilayer, and finds that the magnetoresistance is related to thermally driven spontaneous spin polarization in chiral molecules.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Multidisciplinary Sciences
Tomoya Higo, Kouta Kondou, Takuya Nomoto, Masanobu Shiga, Shoya Sakamoto, Xianzhe Chen, Daisuke Nishio-Hamane, Ryotaro Arita, Yoshichika Otani, Shinji Miwa, Satoru Nakatsuji
Summary: This study demonstrates the perpendicular and full spin-orbit torque switching of an antiferromagnetic binary state. The researchers use the chiral antiferromagnet Mn3Sn and fabricate heavy-metal/Mn3Sn heterostructures by molecular beam epitaxy. The experimental results show that the perpendicular octupole polarization in a 30-nanometre-thick Mn3Sn film can achieve 100% switching with a critical current density of less than 15 megaamperes per square centimetre. The study reveals the significance of the perpendicular geometry between the current-induced spin accumulation and the octupole polarization for spin-orbit torque efficiency.
Article
Chemistry, Multidisciplinary
Yunyoung Hwang, Jorge Puebla, Kouta Kondou, Yoshichika Otani
Summary: This study investigates the surface acoustic waves (SAWs) driven ferromagnetic resonance (FMR) and the inverse Edelstein effect (IEE) voltage signals under external magnetic fields. It is found that with an increase in the out-of-plane component of the external magnetic field, the voltage signal exhibits a sum of even and odd signal contributions, suggesting the presence of a novel resonant spin rectification mechanism.
ADVANCED MATERIALS INTERFACES
(2022)
Article
Nanoscience & Nanotechnology
Mingxing Wu, Kouta Kondou, Taishi Chen, Satoru Nakatsuji, Yoshichika Otani
Summary: In this study, the magnetotransport properties of a microfabricated Mn3Ge single crystal were investigated. Anomalous anisotropic magnetoresistance with fourfold symmetry and positive high-field longitudinal magnetoresistance below the critical temperature were observed. The temperature-induced tilting of the Weyl nodes may be the possible cause. This study contributes to the understanding of magnetotransport properties in the Weyl fermion system.
Review
Physics, Multidisciplinary
Kouta Kondou, Yoshichika Otani
Summary: Spin-charge conversion (SCC) is the driving principle of spintronics devices, which can create non-volatile magnetic memory and energy harvesting devices that convert light, sound, and heat into charge current. Controllable SCCs have recently emerged in materials with spatial and time-reversal asymmetry, providing a new pathway for efficient manipulation and realization of novel functionalities in spintronics devices. This study provides an overview of the fundamental mechanism of SCC and recent research progress in novel materials, including topological magnets and atomically layered materials. Additionally, the emergence of spin functionalities in chiral organic materials is discussed.
FRONTIERS IN PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Ryoya Nakamura, Masashi Tokuda, Mori Watanabe, Masamichi Nakajima, Kensuke Kobayashi, Yasuhiro Niimi
Summary: Flux pinning in exfoliated FeTe0.6Se0.4 thin-film devices was studied, where strong pinning is dominant below approximately 70 nm thickness and weak collective pinning becomes more important above approximately 100 nm thickness. This crossover thickness phenomenon can be explained by a theoretical model proposed by van der Beek et al.
Article
Materials Science, Multidisciplinary
Shuichi Iwakiri, Satoshi Sugimoto, Yasuhiro Niimi, Yusuke Kozuka, Yukiko K. Takahashi, Shinya Kasai, Kensuke Kobayashi
Summary: The study reveals a clear negative correlation between the linear and lowest-order nonlinear currents in the current-voltage characteristics of magnetic tunnel junctions (MTJ), which is independent of temperature and tunnel barrier thickness. A proposed phenomenological model based on the Julliere model attributes this negative correlation to spin-flip tunneling assisted by a magnon, suggesting a fundamental law governing the linear and nonlinear responses of MTJ.
