Article
Multidisciplinary Sciences
Carlos Escuin, Pablo Ibanez, Denis Navarro, Teresa Monreal, Jose M. Llaberia, Victor Vinals
Summary: This paper presents a novel LLC organization and a forecasting method for NV-LLC lifetime. The method combines detailed simulation and prediction to analyze the impact of different cache control policies and mechanisms on the temporal evolution of NV-LLC. A new LLC design, L2C2, is also introduced, which combines fault tolerance, compression, and internal write wear leveling to increase the lifetime of NV-LLC.
Article
Computer Science, Hardware & Architecture
Ahmet Inci, Mehmet Meric Isgenc, Diana Marculescu
Summary: This study introduces the DeepNVM++ framework for characterizing, modeling, and analyzing NVM-based caches in GPU architectures. By combining technology-specific circuit-level models and memory behavior of various DL workloads, it shows that STT-MRAM and SOT-MRAM offer significant advantages in performance and energy over SRAM.
IEEE TRANSACTIONS ON COMPUTER-AIDED DESIGN OF INTEGRATED CIRCUITS AND SYSTEMS
(2022)
Article
Chemistry, Physical
Gergely Tarsoly, Jae-Yun Lee, Fei Shan, Sung-Jin Kim
Summary: This paper presents a resistive memory based on TiO2 and a-IGZO thin films with optimized annealing temperature. The study proposes a memory mechanism and demonstrates low voltage operation, good retention stability, and endurance stability of the device.
APPLIED SURFACE SCIENCE
(2022)
Review
Computer Science, Information Systems
Weijian Chen, Zhi Qi, Zahid Akhtar, Kamran Siddique
Summary: This paper discusses various methods and design schemes for ReRAM-based PIM neural network accelerators, and addresses the limitations or challenges of ReRAM in a neural network.
Article
Engineering, Electrical & Electronic
Hugo Nicolas, Ricardo C. Sousa, Ariam Mora-Hernandez, Ioan-Lucian Prejbeanu, Luc Hebrard, Jean-Baptiste Kammerer, Joris Pascal
Summary: This article presents a new type of magnetic sensor using a perpendicular spin transfer torque magnetic tunnel junction (MTJ). The sensor has a cylindrical shape with a diameter of 50 nm, making it one of the smallest magnetic sensors reported. The article discusses the principle of operation, signal processing electronics, experimental results, and comparisons to existing magnetic sensors. The sensor demonstrates high sensitivity and dynamic range, and its compatibility with standard microelectronics components allows for integration with conditioning electronics.
IEEE SENSORS JOURNAL
(2023)
Article
Engineering, Electrical & Electronic
Manoj Kumar Yadav, Santosh Kumar Gupta
Summary: This study presents a first principle analysis of Fe/MgO/Fe magnetic tunnel junctions (MTJ) with gate voltage control over the insulated barrier region. The results show that the different work functions of the gate and barrier materials lead to the transfer of density of states (DOS) in the forbidden energy gap of MgO due to the Schottky effect. The high spin injection efficiency and tunnel magneto resistance (TMR) ratios observed in this study indicate the potential of MTJs as three-terminal devices for magnetic random access memory (MRAM) applications.
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
Computer Science, Information Systems
Felipe Pinto, Ioannis Vourkas
Summary: Research has been conducted on utilizing memristors for basic logical operations, but system-level design of computational memories has not been fully considered. This study proposes a design for a ReRAM-based general-purpose computational memory, with performance characteristics validated through circuit simulations.
Article
Engineering, Electrical & Electronic
Thomas Abbey, Christos Giotis, Alex Serb, Spyros Stathopoulos, Themis Prodromakis
Summary: This research examines the effects of temperature on the volatility of resistive RAM (RRAM) and proposes a model that incorporates these temperature effects into the previously developed model for volatile switching. The study reveals the impact of device temperature on resistive state magnitude and relaxation time constant, with polarity also playing a role.
IEEE ELECTRON DEVICE LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Hugo Nicolas, Ricardo C. Sousa, Ariam Mora-Hernandez, Ioan-Lucian Prejbeanu, Luc Hebrard, Jean-Baptiste Kammerer, Joris Pascal
Summary: This article presents a new type of magnetic sensor using a perpendicular spin transfer torque magnetic tunnel junction (MTJ). The sensor has a cylindrical shape with a diameter of 50 nm, making it one of the smallest ever reported. The article describes the principle of operation, signal processing electronics, and compares its performance with commercially available sensors. The developed sensor has a sensitivity of 1.28 V/T, a dynamic range of 80 mT, and a noise level of 21.8 μT/√Hz. The sensor and its electronics are compatible with existing fabrication processes, allowing for mass production in various markets.
IEEE SENSORS JOURNAL
(2023)
Article
Engineering, Electrical & Electronic
Ramit Dutta, Shafin Bin Hamid, Jia Hao Lim, Joel Tan, Bejoy Sikder, Nagarajan Raghavan, Kin Leong Pey, Md Zunaid Baten
Summary: The impact of intracell magnetic coupling on the device-to-device variability of STT-MRAMs is investigated through experiments and simulations. It is found that the measured switching voltages of CoFeB/MgO STT-MRAMs are correlated with the offset fields from magnetic measurements. The correlation is traced back to the stray field arising from intracell magnetic coupling.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Engineering, Electrical & Electronic
Christopher Muench, Nour Sayed, Rajendra Bishnoi, Mehdi Tahoori
Summary: This study introduces a new technique for in-memory computing using resistive devices, which can efficiently compute symmetric Boolean logic operations for any number of inputs. By converting the equivalent resistance state generated by storing devices into electrical oscillations and using time-based sensing to generate outputs, it improves dynamic energy and scalability. It implements an efficient error-correction code (ECC) for in-memory computing and has been validated through extensive Monte Carlo simulations in the presence of process variation.
IEEE TRANSACTIONS ON MAGNETICS
(2021)
Article
Materials Science, Multidisciplinary
Shahnaz Kossar, R. Amiruddin, Asif Rasool, M. C. Santhosh Kumar, Nagamalleswari Katragadda, Pranab Mandal, Nafis Ahmed
Summary: In this study, Nd-doped Bismuth Ferrite (BFO) thin film layers were prepared using a spray pyrolysis method. The higher Nd doping concentration led to a change in structural characteristics of the thin films, while XPS analysis showed an improved Fe 3+/Fe 2+ ratio and reduced oxygen vacancy defects. The fabricated RS device based on Nd-doped BFO demonstrated a high remnant polarization and stable RS characteristics, especially with 7% Nd doping.
CURRENT APPLIED PHYSICS
(2022)
Article
Physics, Applied
Fangcen Zhong, Masanori Natsui, Takahiro Hanyu
Summary: This paper presents a technique for stabilizing the operation of NV-LSIs by minimizing inrush current effects and voltage fluctuations, which can effectively reduce static power consumption and enhance performance.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Computer Science, Hardware & Architecture
Satyajaswanth Badri, Mukesh Saini, Neeraj Goel
Summary: This article proposes an architecture that ensures safe backup of volatile contents during a power failure under energy constraints. By using the proposed dirty block table (DBT) and writeback queue (WBQ), the number of dirty blocks in the L1 cache is limited. The proposed architecture decreases energy consumption by 17.56% and reduces the number of writes to NVM at LLC and main-memory level compared to the baseline architecture.
IEEE TRANSACTIONS ON VERY LARGE SCALE INTEGRATION (VLSI) SYSTEMS
(2023)
Article
Physics, Applied
Junta Igarashi, Butsurin Jinnai, Valentin Desbuis, Stephane Mangin, Shunsuke Fukami, Hideo Ohno
Summary: This study investigates the energy barrier relevant to the retention property in CoFeB/MgO-based shape-anisotropy MTJs at high temperatures and finds a scaling relationship between the energy barrier and spontaneous magnetization. The scaling exponent for shape-anisotropy MTJs is much smaller than for interfacial-anisotropy MTJs, indicating less sensitivity to temperature. The study discusses the design window of MTJ dimensions for achieving 10-year data retention at various temperatures.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Butsurin Jinnai, Junta Igarashi, Kyota Watanabe, Eli Christopher I. Enobio, Shunsuke Fukami, Hideo Ohno
Summary: The study shows that in shape-anisotropy magnetic tunnel junctions, magnetization reversal proceeds coherently in the 15-nm-thick CoFeB layer, which is different from conventional interfacial-anisotropy MTJs. Evaluation of the thermal stability factor Delta using two methods is crucial for the development of ultra-small and high-reliability MTJ devices.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Chaoliang Zhang, Yutaro Takeuchi, Shunsuke Fukami, Hideo Ohno
Summary: In this study, we investigate the magnetization switching using a combination of STT and SOT, finding that SOT allows for fast switching of magnetization and STT eliminates the need for an external field. The results show that in the short pulse regime, the Type X structure achieves a switching current one-fourth smaller than the Type Y structure at 200 ps.
APPLIED PHYSICS LETTERS
(2021)
Article
Engineering, Electrical & Electronic
M. Niwa, K. Kimura, T. Naijo, A. Oshurahunov, S. Nagamachi, H. Inoue, H. Honjo, S. Ikeda, T. Endoh
Summary: The study successfully observed the microstructure of nano-scale CoFeB-MgO-based magnetic tunnel junctions, identified the root cause of resistance changes, determined the composition of the altered region inside the MTJ, and confirmed the effectiveness of STEM tomography in failure analysis.
IEEE TRANSACTIONS ON MAGNETICS
(2021)
Article
Engineering, Electrical & Electronic
Hiroki Koike, Takaho Tanigawa, Toshinari Watanabe, Takashi Nasuno, Yasuo Noguchi, Mitsuo Yasuhira, Toru Yoshiduka, Yitao Ma, Hiroaki Honjo, Koichi Nishioka, Sadahiko Miura, Hirofumi Inoue, Shoji Ikeda, Tetsuo Endoh
Summary: The development of STT-MRAM technology is ongoing and faces challenges such as further device scaling. A new circuit proposed in the study using an averaged reference voltage generator successfully reduced the fail bit rate. Through simulations and design of a 128 Mb STT-MRAM chip, the operation of the proposed device-variation tolerant array architecture was demonstrated successfully for the first time.
IEEE TRANSACTIONS ON MAGNETICS
(2021)
Article
Nanoscience & Nanotechnology
Yoshiaki Saito, Nobuki Tezuka, Shoji Ikeda, Tetsuo Endoh
Summary: The artificially synthesized (W/Hf)-multilayer systems can enhance the spin-Hall effect and control the value of spin diffusion length. Additionally, the systems prepared under low-Ar-pressure condition can achieve a more highly oriented MgO (100) texture on CoFeB, making them suitable for magnetic tunnel junctions with high tunnel magnetoresistance properties.
Article
Nanoscience & Nanotechnology
H. Honjo, H. Naganuma, T. V. A. Nguyen, H. Inoue, M. Yasuhira, S. Ikeda, T. Endoh
Summary: The study showed that applying SMT to the bottom Pt layer increased the PMA of the overlying Co/Pt multilayer, leading to better thermal tolerance and magnetic properties of the MTJs with a Co/Pt synthetic ferrimagnetic coupling reference layer.
Article
Nanoscience & Nanotechnology
K. Nishioka, H. Honjo, H. Naganuma, T. V. A. Nguyen, M. Yasuhira, S. Ikeda, T. Endoh
Summary: The research shows that the thickness of the W insertion layer affects the magnetic coupling energy and effective perpendicular magnetic anisotropy in conventional double-MTJs. There is a trade-off relationship between J(cpl) and K(eff)t(*), but adding a ferromagnetic bridge layer can improve J(cpl) while maintaining the maximum value of K(eff)t(*).
Correction
Physics, Applied
Butsurin Jinnai, Junta Igarashi, Kyota Watanabe, Eli Christopher I. Enobio, Shunsuke Fukami, Hideo Ohno
APPLIED PHYSICS LETTERS
(2021)
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
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
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.
