Article
Chemistry, Physical
Xiaobing Hu, Hao Chen, Dongxia Tian, Xiaorong Niu, Xiaojie Chai, Shengbo Sang
Summary: Ferroelectric domain-wall random access memory (DWRAM) based on highly conductive domain walls in insulating ferroelectric LiNbO3 (LNO) thin films has great potential for future memory storage. The passivation layer in the vertically integrated structure (VIS) architecture plays a critical role in the memory's retention, on/off current ratio, and reliability. This study investigates the strain of silicon nitride and silicon dioxide as passivation layers and proposes a Si3N4/SiO2 composite passivation layer to solve the residual strain issue and ensure good insulation performance. A crossbar array of DW memory cells with high on/off current ratio was successfully fabricated using the Si3N4/SiO2 composite layer, demonstrating the feasibility of high-density integration of LNO domain wall memories.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Engineering, Electrical & Electronic
Arifa Hogue, Alex K. Jones, Sanjukta Bhanja
Summary: This study introduces a novel 2-D DWM cross-point structure that enables logical shifting and data movement of nanowires, supporting processing-in-memory. The requirements for physical dimensions and shift currents have been investigated, and experimental results demonstrate the feasibility of this structure.
IEEE TRANSACTIONS ON NANOTECHNOLOGY
(2022)
Article
Materials Science, Multidisciplinary
Ting-Ting Liu, Yi-Fei Hu, Yang Liu, Zhe-Jun-Yu Jin, Zheng-Hua Tang, Ming-Hui Qin
Summary: In this study, the domain wall motion in ferrimagnets driven by a circularly polarized magnetic field was investigated using the collective coordinate theory and atomistic micromagnetic simulations. The effect of the Dzyaloshinskii-Moriya interaction (DMI) was particularly studied. The results showed that the ferrimagnetic wall moved at a speed linearly dependent on the magnitude of DMI, similar to the case of antiferromagnetic domain wall. Additionally, the DMI was found to modulate the domain wall dynamics in a similar way to the net spin density, providing another internal parameter for controlling the domain wall in ferrimagnets. Moreover, the study demonstrated that the domain wall dynamics in ferrimagnets were much faster than those in ferromagnets, confirming the high potential of ferrimagnets in future spintronic applications.
Article
Physics, Applied
Yuushou Hirata, Kaoru Noda, Yoichi Shiota, Takahiro Moriyama, Teruo Ono
Summary: In the study of field-driven domain wall creep motion in ferrimagnetic Tb/CoFeB/MgO, it was found that the domain wall velocity increases with increasing CoFeB thickness. The characteristic velocity at which the domain wall moves when the energy barrier vanishes is a dominant contribution to the domain wall velocity, clarifying the ferrimagnetic domain wall dynamics in the creep regime.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2021)
Article
Engineering, Electrical & Electronic
Patrick Girard, Yuanqing Cheng, Arnaud Virazel, Weisheng Zhao, Rajendra Bishnoi, Mehdi B. Tahoori
Summary: Memories are a significant part of system-on-chips and contribute to the system power consumption. This article discusses the potential of magnetic random access memories to mitigate Flash shortcomings and be used as replacements for DRAM and SRAM. It provides an up-to-date coverage of MRAM test and reliability solutions in the literature, focusing on defectiveness and reliability issues.
PROCEEDINGS OF THE IEEE
(2021)
Article
Engineering, Electrical & Electronic
Manman Wang, Yanfeng Jiang
Summary: MTJ based on CIDWM has the potential to mimic non-volatile artificial neuron and synapse, with the advantages of low power consumption and high propagation speed.
IEEE TRANSACTIONS ON MAGNETICS
(2022)
Article
Chemistry, Multidisciplinary
Luka Skoric, Claire Donnelly, Aurelio Hierro-Rodriguez, Miguel A. Cascales Sandoval, Sandra Ruiz-Gomez, Michael Foerster, Miguel A. Nino, Rachid Belkhou, Claas Abert, Dieter Suess, Amalio Fernandez-Pacheco
Summary: This study proposes a three-dimensional magnetic interconnector that utilizes geometry-driven automotion of domain walls for magnetic information transfer between functional magnetic planes. Through experiments and simulations, it is found that large thickness gradients in the structure are the main mechanism for the automotion of domain walls. This work demonstrates a possible mechanism for efficient transfer of magnetic information in three dimensions.
Article
Engineering, Electrical & Electronic
Eline Raymenants, Danny Wan, Sebastien Couet, Laurent Souriau, Arame Thiam, Diana Tsvetanova, Yann Canvel, Kevin Garello, Gouri S. Kar, Marc Heyns, Inge Asselberghs, Dmitri E. Nikonov, Ian A. Young, Stefania Pizzini, Iuliana Radu, Van Dai Nguyen
Summary: Spin logic devices based on domain wall motion can be fully electrically controlled using a novel MTJ stack, offering potential solutions for high-performance and low-power applications.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Engineering, Electrical & Electronic
Zhen Cao, Shuai Zhang, Jian Zhang, Nuo Xu, Ruofan Li, Zhe Guo, Jijun Yun, Min Song, Qiming Zou, Li Xi, Oukjae Lee, Xiaofei Yang, Xuecheng Zou, Jeongmin Hong, Long You
Summary: A reliable physical unclonable function (PUF) design based on spin-orbit torque induced domain wall motion has been proposed and experimentally demonstrated. The device-to-device variation enables PUF functionality, while cycle-to-cycle variation in domain wall motion enables reconfigurable design. This anti-counterfeiting device based on domain wall motion shows good potential as a CMOS-compatible PUF for hardware security.
IEEE ELECTRON DEVICE LETTERS
(2021)
Article
Materials Science, Multidisciplinary
M. Al Bahri
Summary: A micromagnetic simulation was used to study the nucleation of transverse domain wall (TDW) and vortex domain wall (VDW) in different nanomagnetic devices based on their thickness, width, and temperature. The stability of TDW and VDW thermal switching in nanowires is strongly influenced by magnetic properties and device geometry. While TDW switching is stable up to 500 K, VDW switching shows higher thermal stability reaching up to 900 K, making them potential candidates for storage applications.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Physics, Applied
Kequn Chi, Yinuo Shi, Zhou Li, Wenbiao Zhang, Yun Xing, Xiang Feng, Yungui Ma, Hao Meng, Bo Liu
Summary: This study demonstrates an L-shaped electrode structure attached to the magnetic recording layer to induce composite SOT for high-speed and field-free magnetization switching. A comparison between L-shaped and sidewall electrode structures shows that the L-shaped structure leads to fast and low-power switching. The novel L-shaped structure is feasible for high-speed, low-power, and deterministic switching with potential in spintronic applications.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Computer Science, Hardware & Architecture
Debasis Das, Xuanyao Fong
Summary: This article discusses various schemes to achieve reset in a magnetic domain wall-based spintronic neuron, highlighting the importance of the reset strategy in improving the energy efficiency of spintronic artificial spiking neurons.
IEEE JOURNAL ON EXPLORATORY SOLID-STATE COMPUTATIONAL DEVICES AND CIRCUITS
(2022)
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
Fabrizio Riente, Domenico Giuliano, Luca Gnoli, Valentin Ahrens, Massimo Ruo Roch, Markus Becherer, Giovanna Turvani, Marco Vacca
Summary: This study demonstrates how Ga+ ion irradiation can be used to modify the material properties and trap domain walls at specific positions. The driving force required to overcome the irradiated regions depends on the ion dose. This reliable approach enables precise control of the domain wall position during motion.
ACS APPLIED ELECTRONIC MATERIALS
(2023)
Article
Engineering, Electrical & Electronic
K. Richter, O. Vahovsky, R. Varga
Summary: This study reveals that tilted domain walls in amorphous glass-coated microwires undergo complex distortions on a local scale.
IEEE TRANSACTIONS ON MAGNETICS
(2022)
Article
Physics, Applied
Yutaro Takeuchi, Ryotaro Okuda, Junta Igarashi, Butsurin Jinnai, Takaharu Saino, Shoji Ikeda, Shunsuke Fukami, Hideo Ohno
Summary: In this study, a thin-film deposition technique for a-few-nanometer-thin L1(0)-MnAl was developed and its structure and magnetic properties were investigated. The results show that L1(0)-MnAl has a large crystalline anisotropy and small spontaneous magnetization, making it a promising material for high-density and high-speed STT-MRAM.
APPLIED PHYSICS LETTERS
(2022)
Article
Engineering, Electrical & Electronic
H. Honjo, H. Naganuma, K. Nishioka, T. V. A. Nguyen, M. Yasuhira, S. Ikeda, T. Endoh
Summary: We investigated the effects of sputtering conditions for the deposition of an Iridium (Ir) layer on the magnetic properties and tunnel magnetoresistance ratio (TMR ratio) of magnetic tunnel junctions (MTJs) stacks. the exchange coupling field (H-ex) of Ir-SyF was improved by reducing the energy of Ir recoil ions and two times larger than that with Ru-SyF. Energy dispersive X-ray (EDX) spectrometry line analysis revealed greater interlayer diffusion in Ir when Ir was sputtered by using a conditions with large recoiled energy. Despite the larger H-ex, the TMR ratio of the MTJ with Ir-SyF is smaller than that with Ru-SyF. The m-H curve of MTJ with Ru-SyF showed a large plateau region around zero magnetic field, whereas that with Ir-SyF did not. These results indicated the degradation of perpendicular magnetic anisotropy (PMA) in the top part of the Co/Pt multilayer with CoFeB reference layer and a large biquadratic coupling effect in the thin Ir layer. This causes the deterioration of the TMR ratio of the MTJ with Ir-SyF. TEM image of the Co/Pt layer in the MTJ with Ir shows some lattice defects. The EDX line analysis revealed that a large amount of Pt in the top Co/Pt layer diffused toward CoFeB reference layer in the Ir-SyF, resulting in the degradation of PMA. The structural analysis by X-ray diffraction showed the lattice spacing of CoPt (111) in Ir-SyF to be larger than that in Ru-SyF, indicating the occurrence of strain relaxation at the Co/Pt interface. These crystallographic changes in Ir-SyF might be related to a larger Pt diffusion. Suppression of Pt diffusion as well as low damage Ir deposition in the reference layer is crucial to utilize Ir-SyF.
IEEE TRANSACTIONS ON MAGNETICS
(2022)
Article
Engineering, Electrical & Electronic
H. Honjo, K. Nishioka, S. Miura, H. Naganuma, T. Watanabe, Y. Noguchi, T. V. A. Nguyen, M. Yasuhira, S. Ikeda, T. Endoh
Summary: Perpendicular magnetic tunnel junctions (MTJs) with four synthetic anti-ferromagnetically coupled Co/Pt layers were developed and showed higher tunnel magnetoresistance ratio and stability at high temperatures compared to conventional double-SyF. In contrast, conventional double-SyF exhibited magnetization direction flipping and back-hopping under external magnetic fields.
IEEE TRANSACTIONS ON MAGNETICS
(2022)
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
Chemistry, Physical
Mohammad Zahedinejad, Himanshu Fulara, Roman Khymyn, Afshin Houshang, Mykola Dvornik, Shunsuke Fukami, Shun Kanai, Hideo Ohno, Johan Akerman
Summary: The study demonstrates that memristive gating of W/CoFeB/MgO/AlOx-based SHNOs can effectively address the challenges of interfacing, tuning, and storing the state of large arrays of SHNOs. The memristor in its high resistance state modulates the perpendicular magnetic anisotropy, while in its low resistance state it adds or subtracts current to the SHNO drive, allowing for reversible turning on/off of mutual synchronization in chains of SHNOs. This approach enables non-volatile tuning of mutual synchronization in chains of up to four oscillators and provides a path toward individual control in large oscillatory arrays.
Article
Physics, Applied
Jan Kaiser, William A. Borders, Kerem Y. Camsari, Shunsuke Fukami, Hideo Ohno, Supriyo Datta
Summary: This paper presents a hardware neural network circuit using spintronics-based neurons, which are built with stochastic magnetic tunnel junctions. The circuit can learn weights and biases in situ and mitigate device-to-device variations. It is suitable for creating standalone artificial intelligence devices capable of fast and efficient learning at the edge.
PHYSICAL REVIEW APPLIED
(2022)
Article
Materials Science, Multidisciplinary
Rajeswari Roy Chowdhury, Chandan Patra, Samik DuttaGupta, Sayooj Satheesh, Shovan Dan, Shunsuke Fukami, Ravi Prakash Singh
Summary: Two-dimensional van der Waals magnets have attracted attention for their magnetic properties and flexibility. This study explores an alternative approach to manipulate magnetotransport properties by doping at the nonmagnetic site, revealing a new method of control.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Physics, Applied
Tomohiro Uchimura, Ju-Young Yoon, Yuma Sato, Yutaro Takeuchi, Shun Kanai, Ryota Takechi, Keisuke Kishi, Yuta Yamane, Samik DuttaGupta, Jun'ichi Ieda, Hideo Ohno, Shunsuke Fukami
Summary: In this study, hysteresis-loop measurement and domain imaging were performed on (1 (1) over bar 00)-oriented D0(19)-Mn3+xSn1-x (-0.11 <= x <= 0.14) thin films using the magneto-optical Kerr effect (MOKE), and the results were compared with the anomalous Hall effect (AHE) measurement. The x dependence of AHE and MOKE showed a similar trend, indicating the same origin. Furthermore, the reversal process of the chiral-spin structure in non-collinear antiferromagnetic thin films was found to start with nucleation of sub-micrometer-scale domains and preferentially propagate along the [11(2) over bar 0] direction.
APPLIED PHYSICS LETTERS
(2022)
Article
Nanoscience & Nanotechnology
T. V. A. Nguyen, Y. Saito, H. Naganuma, S. Ikeda, T. Endoh, Y. Endo
Summary: The dynamic magnetic properties of Ta-O/Co20Fe60B20 bilayer films are greatly influenced by the oxidation condition of the Ta-O layer. The oxidation of the Ta-O layer leads to a decrease in the in-plane damping constant and an increase in the effective magnetization. The out-of-plane damping constant shows a similar trend but with a much smaller magnitude compared to the in-plane damping constant.
Article
Physics, Applied
Yuma Sato, Yutaro Takeuchi, Yuta Yamane, Ju-Young Yoon, Shun Kanai, Jun'ichi Ieda, Hideo Ohno, Shunsuke Fukami
Summary: The thermal stability of antiferromagnetic Mn3Sn nanodots was studied, and the results showed that the thermal stability factor decreases when the diameter is smaller than 300 nm. These findings provide a basis for understanding the thermal fluctuation and reversal mechanism of antiferromagnets for device applications.
APPLIED PHYSICS LETTERS
(2023)
Review
Chemistry, Physical
Jiahao Han, Ran Cheng, Luqiao Liu, Hideo Ohno, Shunsuke Fukami
Summary: Antiferromagnets have attracted extensive interest in spintronics and various applications have been developed based on the coherent effects of antiferromagnet dynamics. This Review categorizes and analyzes the critical effects, including spin pumping, spin transmission, electrically induced spin rotation and ultrafast spin-orbit effects, that harness the coherence of antiferromagnets for spintronic applications. Future opportunities in research and applications in coherent antiferromagnetic spintronics are also discussed.
Article
Computer Science, Hardware & Architecture
Shuvro Chowdhury, Andrea Grimaldi, Navid Anjum Aadit, Shaila Niazi, Masoud Mohseni, Shun Kanai, Hideo Ohno, Shunsuke Fukami, Luke Theogarajan, Giovanni Finocchio, Supriyo Datta, Kerem Y. Camsari
Summary: The transistor turned 75 in 2022 and continues to scale, albeit at a slower pace dictated by Moore's law. In the face of increasing computing demands and energy consumption of modern AI algorithms, integrating transistors with unconventional technologies has become a promising approach for domain-specific computing.
IEEE JOURNAL ON EXPLORATORY SOLID-STATE COMPUTATIONAL DEVICES AND CIRCUITS
(2023)
Article
Materials Science, Multidisciplinary
Motoya Shinozaki, Junta Igarashi, Shuichi Iwakiri, Takahito Kitada, Keisuke Hayakawa, Butsurin Jinnai, Tomohiro Otsuka, Shunsuke Fukami, Kensuke Kobayashi, Hideo Ohno
Summary: Magnetic tunnel junctions (MTJs) with spin-dependent conductance were investigated in this study. The nonlinear conductance at low bias regime was evaluated in nanoscale MTJs. The relationships between different conductance components were examined. The results indicated that the conductance components were correlated with the junction size and external magnetic field. The findings provide insights into the electron transport mechanism in nanoscale MTJs.
Article
Materials Science, Multidisciplinary
Yoshiaki Saito, Shoji Ikeda, Tetsuo Endoh
Summary: Investigation on spin-orbit torque in synthetic antiferromagnetic structures reveals higher spin-torque efficiency in stack systems with Pt/Ir/Pt spacer layer. This finding contributes to the improvement of magnetic memory device performance.
