Article
Engineering, Electrical & Electronic
Clemens Muehlenhoff, Michal Krupinski, Arkadiusz Zarzycki, Manfred Albrecht
Summary: In this study, the magnetotransport properties of Co/Pt based perpendicular synthetic antiferromagnetic (p-SAF) structures with Ru interlayers were investigated. The number of Co/Pt multilayer (ML) stacks and Ru interlayers in the p-SAF structures were varied to examine changes in their magnetoresistive effects. The alignment of magnetization directions of the MLs in the ML/Ru/ML stacks of the p-SAF generated a giant magnetoresistance effect (GMR), while the anisotropic magnetoresistance effect (AMR) at each ML further influenced the resistance of the system. The study results have important implications for understanding and application of magnetoresistive effects.
IEEE SENSORS JOURNAL
(2022)
Article
Engineering, Electrical & Electronic
Odilia Coi, Gregory Di Pendina, Ricardo Sousa, Nomena Adrianjohany, David Dangla, Robert Ecoffet, Lionel Torres
Summary: This article investigates the effects of heavy-ion irradiation on PMA STT-MTJ devices, specifically focusing on the SEU tolerance and modification of magnetic properties of STT p-MTJs purely magnetic memories.
IEEE TRANSACTIONS ON NUCLEAR SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
Pravin Khanal, Bowei Zhou, Magda Andrade, Christopher Mastrangelo, Ali Habiboglu, Arthur Enriquez, Daulton Fox, Kennedy Warrilow, Wei-Gang Wang
Summary: It is found that reactive RF sputtering with O-2 is essential to obtain strong perpendicular magnetic anisotropy and large tunneling magnetoresistance in MgAl2O4-based junctions. An interfacial perpendicular magnetic anisotropy energy density of 2.25 mJ/m(2) is obtained for the samples annealed at 400 C. An enhanced magnetoresistance of 60% has also been achieved. The V-half,V- bias voltage at which tunneling magnetoresistance drops to half of the zero-bias value, is found to be about 1 V, which is substantially higher than that of MgO-based junctions.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Trevor P. Almeida, Steven Lequeux, Alvaro Palomino, Ricardo C. Sousa, Olivier Fruchart, Ioan-Lucian Prejbeanu, Bernard Dieny, Aurelien Masseboeuf, David Cooper
Summary: This study investigates the magnetism of a NiFe PSA-STT-MRAM nanopillar using off-axis electron holography. The results show that the PSA of the nanopillar is maintained up to at least 250 degrees Celsius, with a moderate decrease in magnetic induction. Therefore, PSA provides significant stability in STT-MRAM applications.
Article
Materials Science, Multidisciplinary
Han Guchang, Zhang Kaiyue, Yang Xiaolei, Ai Libo, Wang Ming, Liu Bo
Summary: This paper investigates the magnetic switching behavior of each layer in perpendicular MTJs, identifying three types of abnormal magnetic behaviors of the reference layer (RL) and their related physical mechanisms. Relevant methods to overcome these abnormal magnetic switching behaviors are suggested and successfully applied in the fabrication of MRAM chips.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2021)
Article
Physics, Condensed Matter
Sergey V. Faleev, Panagiotis Ch. Filippou, Chirag Garg, Jaewoo Jeong, Mahesh G. Samant, Stuart S. P. Parkin
Summary: This article proposes a mechanism for thin films made of Heusler compounds to simultaneously have perpendicular magnetic anisotropy (PMA) and be half-metallic. It is suggested that the thin film can undergo a tetragonal distortion by adopting the lattice constant of the underlayer material during deposition. The distortion can be tuned by using underlayer materials with different in-plane lattice constants, optimizing it to provide sufficient PMA while retaining the half-metallic properties of the Heusler compound.
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Bjoern Bueker, JinWon Jung, Taisuke Sasaki, Yuya Sakuraba, Yoshio Miura, Tomoya Nakatani, Andreas Huetten, Kazuhiro Hono
Summary: The study demonstrates that even a monolayer near the interface critically affects the interfacial band matching and magnetoresistance properties between ferromagnetic and nonmagnetic metals.
Review
Engineering, Electrical & Electronic
Amogh Agrawal, Cheng Wang, Tanvi Sharma, Kaushik Roy
Summary: This overview article discusses the tradeoffs and design challenges of Magnetoresistive Random Access Memory (MRAM) in various application areas, highlighting its potential for replacing standard CMOS memories and accelerating matrix-vector-multiplication operations. It also explores how the inherent stochasticity of MRAM devices can be utilized to implement energy-efficient true random number generators and stochastic units for specific tasks.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS
(2021)
Article
Physics, Applied
Xinlu Li, Yurong Su, Meng Zhu, Fanxing Zheng, Peina Zhang, Jia Zhang, Jing-Tao Lu
Summary: The study reveals a vdW CPP GMR with significant advantages, including perpendicular magnetic anisotropy, large GMR, low RA, and sizable AMR, which mainly originate from the bulk electronic structure properties of Fe3GeTe2. This work may stimulate future experimental explorations and have potential applications in spintronic devices.
PHYSICAL REVIEW APPLIED
(2021)
Article
Engineering, Electrical & Electronic
Yu-Ching Liao, Chia-Sheng Hsu, Dmitri Nikonov, Sou-Chi Chang, Hai Li, Ian A. Young, Azad Naeemi
Summary: This study investigates the potential performance of magnetoelectric magnetic random access memory (ME-MRAM) using a bismuth ferrite (BFO)/CoFe heterojunction. Circuit-compatible models and micromagnetic simulations were used to analyze the write and read performances of ME-MRAM. The results show that ME-MRAM has lower energy consumption and a smaller layout area compared to SRAM and other spintronic memory candidates.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Engineering, Electrical & Electronic
T. Patrick Xiao, Christopher H. Bennett, Frederick B. Mancoff, Jack E. Manuel, David R. Hughart, Robin B. Jacobs-Gedrim, Edward S. Bielejec, Gyorgy Vizkelethy, Jijun Sun, Sanjeev Aggarwal, Reza Arghavani, Matthew J. Marinella
Summary: The study evaluated the resilience of CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) with perpendicular magnetic anisotropy (PMA) to displacement damage induced by heavy-ion irradiation. It found that damage to the MgO interfaces led to a decrease in magnetoresistance and PMA, elucidating the thresholds for significant irreversible changes in the characteristics of STT-MRAM devices.
IEEE TRANSACTIONS ON NUCLEAR SCIENCE
(2021)
Article
Nanoscience & Nanotechnology
Zeliang Ren, Bin Lao, Xuan Zheng, Lei Liao, Zengxing Lu, Sheng Li, Yongjie Yang, Bingshan Cao, Lijie Wen, Kenan Zhao, Lifen Wang, Xuedong Bai, Xianfeng Hao, Zhaoliang Liao, Zhiming Wang, Run-Wei Li
Summary: This study reports the epitaxial growth of magnetic insulator films with strong perpendicular magnetic anisotropy and their potential application in spintronic devices. The films exhibit high crystalline quality, ferrimagnetic and insulating transport characteristics, as well as pronounced spin Hall magnetoresistance and spin Hall-like anomalous Hall effect in constructed heterostructures.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Engineering, Electrical & Electronic
Keisuke Morishita, Yosuke Harashima, Masaaki Araidai, Tetsuo Endoh, Kenji Shiraishi
Summary: In this study, the effects of grain boundaries in the MgO layer on the interfacial perpendicular magnetic anisotropy (iPMA) were investigated using first-principles calculations. It was found that the presence of grain boundaries leads to a reduction in iPMA. Additionally, the bond structure of Fe-d orbitals around the grain boundaries was identified as a key factor controlling iPMA.
IEEE TRANSACTIONS ON MAGNETICS
(2023)
Article
Engineering, Electrical & Electronic
Hao Cai, Yanan Guo, Bo Liu, Mingyang Zhou, Juntong Chen, Xinning Liu, Jun Yang
Summary: This paper proposes a novel tunneling magnetoresistance (TMR) ratio magnifying method based on MTJ cells to realize analog in-memory computing (IMC). By addressing the concerns of low TMR ratio and analog calculation nonlinearity through device-circuit interaction, the proposed design achieves reduced integral nonlinearity and high energy efficiency for convolutional neural network computations. Simulation results using the 28-nm CMOS process and MTJ compact model show a 57.6% decrease in integral nonlinearity and 9.47-25.4 TOPS/W performance for 2-bit input, 1-bit weight, and 4-bit output CNN computations.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS
(2022)
Article
Nanoscience & Nanotechnology
Ming Cheng, Zhenhua Zhang, Xiaojuan Yuan, Yong Liu, Zhihong Lu, Rui Xiong, Jing Shi
Summary: This study investigated the interface structure and MAE properties of Co2FeAl/MgAl2O4 heterostructures with high PMA using first principles calculations. The results showed that the Co-O interface can induce a large PMA effect, but is a metastable structure, while the FeAl-O interface has a smaller PMA effect. Additionally, enhancing the PMA effect of the FeAl-O interface can be achieved by adjusting strain, electric field, and doping.
Article
Chemistry, Multidisciplinary
Mina Ghanimi Fard, Zahra Khabir, Philipp Reineck, Nicole M. Cordina, Hiroshi Abe, Takeshi Ohshima, Sagar Dalal, Brant C. Gibson, Nicolle H. Packer, Lindsay M. Parker
Summary: This study developed a novel method to target glycan receptors in different brain cell types using lectin-conjugated nanodiamonds. The results demonstrate that the uptake of lectin-conjugated nanodiamonds varies across different types of brain cells.
NANOSCALE ADVANCES
(2022)
Article
Physics, Applied
Ryota Katsumi, Takeshi Hizawa, Akihiro Kuwahata, Shun Naruse, Yuji Hatano, Takayuki Iwasaki, Mutsuko Hatano, Fedor Jelezko, Shinobu Onoda, Takeshi Ohshima, Masaki Sekino, Takashi Yatsui
Summary: This study demonstrates the hybrid integration of a silicon nitride grating structure on a single-crystal diamond, enabling the implementation of nanostructures in diamond without complicated nanofabrication processes. The integrated grating structure enhances the collected NV emissions and improves the magnetic sensitivity of the device.
APPLIED PHYSICS LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Masayuki Tsutsumi, Tatsuya Meguro, Akinori Takeyama, Takeshi Ohshima, Yasunori Tanaka, Shin-Ichiro Kuroki
Summary: Radiation-hardened CMOS image sensors (CIS) with 4H-SiC photosensors and APS-type circuits were developed and demonstrated. The 4H-SiC photodiodes had a dark current of <2 nA/cm(2), and their spectral sensitivity was evaluated from 200 nm to 400 nm. The photosensors showed a maximal quantum efficiency of 63% at 270 nm and high responses to UV light. After exposure to 2 MGy irradiation, the APS-type photosensors still functioned with a dark current of 25 nA/cm(2).
IEEE ELECTRON DEVICE LETTERS
(2023)
Article
Physics, Multidisciplinary
Daniil M. Lukin, Melissa A. Guidry, Joshua Yang, Misagh Ghezellou, Sattwik Deb Mishra, Hiroshi Abe, Takeshi Ohshima, Jawad Ul-Hassan, Jelena Vuckovic
Summary: This study reports on the integration of near-transform-limited silicon vacancy (VSi) defects into microdisk resonators fabricated in a CMOS-compatible 4H-silicon carbide-on-insulator platform. It demonstrates a single-emitter cooperativity of up to 0.8 and optical superradiance from a pair of color centers coupled to the same cavity mode. The effect of multimode interference on the photon scattering dynamics from this multiemitter cavity quantum electrodynamics system is investigated. These results are crucial for the development of quantum networks in silicon carbide and bridge the classical-quantum photonics gap by uniting optically coherent spin defects with wafer-scalable, state-of-the-art photonics.
Article
Nanoscience & Nanotechnology
Shingo Sotoma, Hiroshi Abe, Yohei Miyanoiri, Takeshi Ohshima, Yoshie Harada
Summary: In this study, methods for controlling the physicochemical properties of SiC nanoparticles were developed, including dispersion, surface coating, functionalization, and selective labeling of biomolecules. A thermal oxidation chemical-etching method was successfully developed to deaggregate and produce a high yield of dispersed, metal-contaminant-free SiC nanoparticles. Additionally, controllable thickness polydopamine and excellent dispersity polyglycerol coatings were demonstrated. Furthermore, a single-pot method was developed for selective labeling of CD44 proteins on cell surfaces through biotin-mediated immunostaining. The methods developed in this study are of great importance for the application of SiC nanoparticles in biomedical research and will greatly accelerate their development and potential applications in bioimaging and biosensing.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Physics, Applied
Tetta Suzuki, Yuichi Yamazaki, Takashi Taniguchi, Kenji Watanabe, Yusuke Nishiya, Yu-ichiro Matsushita, Kazuya Harii, Yuta Masuyama, Yasuto Hijikata, Takeshi Ohshima
Summary: In this study, two thermal treatment methods were used to successfully generate negatively charged boron vacancies (V (B) (-)) in hexagonal boron nitride with superior spin properties. Both methods improved the signal-to-noise ratio of the optically detected magnetic resonance signal by a factor of 4. Furthermore, the crystal distortion reflected by the zero-field splitting parameter E significantly reduced after irradiation above 650 degrees C. These findings indicate that thermal treatment is an effective method for a V (B) (-) based quantum sensor.
APPLIED PHYSICS EXPRESS
(2023)
Article
Physics, Applied
C. T. -K. Lew, V. K. Sewani, N. Iwamoto, T. Ohshima, J. C. Mccallum, B. C. Johnson
Summary: Spin defects in solid-state sensors are investigated for their magnetic sensitivity, with potential applications in various industries. The study utilizes a silicon carbide pn-junction diode to detect a spin defect ensemble and enhance the baseline sensitivity through the hyperfine-induced spin-mixing effect observed at zero magnetic field. Additional electron-hole pairs are generated through above bandgap optical excitation, and a balanced detection scheme is implemented to reject common-mode noise, achieving an ultimate sensitivity of 30 nT/root Hz. Both techniques greatly enhance the magnetic sensitivity of the device by a total factor of approximately 24, paving the way for sub-nanotesla magnetic field sensitivities with electrical detection.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
Tamotsu Okamoto, Fumiya Furumaki, Eiku Sato, Ippei Isogai, Yuji Kurimoto, Yasuki Okuno, Mitsuru Imaizumi, Masafumi Akiyoshi, Takeshi Ohshima
Summary: In this study, the effects of He ion and electron beam irradiation on substrate-type CdTe solar cells for detecting alpha and beta radiation were investigated. The induced current in the CdTe solar cell dosimeter increased proportionally with He ion current, indicating its potential for alpha radiation detection. The induced current in the dosimeter also showed proportionality to electron flux, with sensitivity depending on electron energy. Furthermore, the substrate-type CdTe solar cell dosimeter demonstrated sufficient resistance to electron beam irradiation, with no significant degradation in short-circuit current observed.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Shu Motoki, Shin-ichiro Sato, Seiichi Saiki, Yuta Masuyama, Yuichi Yamazaki, Takeshi Ohshima, Koichi Murata, Hidekazu Tsuchida, Yasuto Hijikata
Summary: In this study, the potential of V-Si(-) defects for magnetic sensors operating at high temperatures was demonstrated, with the resonance frequency of the ground level being independent of temperature, indicating the possibility of calibration-free magnetic sensors in temperature-varying environments. The results also showed a linear relationship between magnetic sensing sensitivity and V-Si(-) concentration.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Physical
Tihomir Knezevic, Eva Jelavic, Yuichi Yamazaki, Takeshi Ohshima, Takahiro Makino, Ivana Capan
Summary: In this study, boron-related defects in low-doped n-type 4H-SiC semitransparent Schottky barrier diodes (SBDs) were investigated using minority carrier transient spectroscopy (MCTS). Boron, introduced during chemical vapor deposition (CVD) crystal growth, led to the presence of shallow (B) and deep boron (D-center) defects, with concentrations as high as 1 x 10(15) cm(-3). Despite the higher concentration of boron compared to nitrogen doping, the steady-state electrical characteristics of the n-type 4H-SiC SBDs remained unaffected.
Article
Chemistry, Physical
Robert Bernat, Tihomir Knezevic, Vladimir Radulovic, Luka Snoj, Takahiro Makino, Takeshi Ohshima, Ivana Capan
Summary: We investigated the impact of large-area 4H-SiC Schottky barrier diodes on the radiation response to ionizing particles. Two diode areas, 1 mm x 1 mm and 5 mm x 5 mm, were compared. We utilized (LiF)-Li-6 and (B4C)-B-10 films as thermal neutron converters on top of the diodes. A thermal neutron efficiency of 5.02% was achieved with (LiF)-Li-6, which is among the highest reported efficiencies. Additionally, a temperature-dependent radiation response to alpha particles was presented, with neutron irradiations conducted in a JSI TRIGA dry chamber and an Am-241 wide-area alpha source used for testing.
Article
Physics, Applied
Hiroki Morishita, Naoya Morioka, Testuri Nishikawa, Hajime Yao, Shinobu Onoda, Hiroshi Abe, Takeshi Ohshima, Norikazu Mizuochi
Summary: In this study, positive contrast in photocurrent detected magnetic resonance (PDMR) of nitrogen-vacancy (N-V) centers in diamond is observed. The sign of the PDMR contrast depends on the difference in the photocurrent generated from the excited states and the metastable state of N-V centers. Additionally, noise suppression using a phase-cycling-based noise-canceling technique is introduced to achieve electrically detected ac magnetic field sensing with a sensitivity of 29 nT Hz-1/2.
PHYSICAL REVIEW APPLIED
(2023)
Article
Chemistry, Multidisciplinary
Islay O. O. Robertson, Sam C. C. Scholten, Priya Singh, Alexander J. J. Healey, Fernando Meneses, Philipp Reineck, Hiroshi Abe, Takeshi Ohshima, Mehran Kianinia, Igor Aharonovich, Jean-Philippe Tetienne
Summary: Detecting magnetic noise from small quantities of paramagnetic spins is achieved using spin defects in hexagonal boron nitride (hBN). Negatively charged boron vacancy defects are created in ultra-thin hBN nanoflakes, and the longitudinal spin relaxation time (T1) is measured. By decorating the dry hBN nanopowder with paramagnetic Gd3+ ions, a clear T1 quenching under ambient conditions is observed, indicating the presence of added magnetic noise. Spin measurements, including T1 relaxometry, can also be performed using solution-suspended hBN nanopowder. These findings demonstrate the potential and versatility of hBN quantum sensors for various sensing applications and pave the way towards a truly 2D, ultrasensitive quantum sensor.
Editorial Material
Physics, Applied
Khalid Hattar, Rudy J. M. Konings, Lorenzo Malerba, Takeshi Ohshima
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
C. t. -k. Lew, V. K. Sewani, T. Ohshima, J. C. McCallum, B. C. Johnson
Summary: Silicon carbide (SiC) power devices are crucial in high voltage electronics, but defects at interfaces and in the bulk affect their reliability and performance. This study presents a charge pumping method to characterize SiC/SiO 2 interface defects in commercial SiC power metal-oxide-semiconductor field-effect transistors (MOSFETs). The method is also used to investigate spin states at the SiC/SiO 2 interface through charge pumping electrically detected magnetic resonance (CP-EDMR).
JOURNAL OF APPLIED PHYSICS
(2023)
