In recent years, there has been a strong demand for soft magnetic films suitable for high-frequency micromagnetic devices as power electronics circuits to operate at higher frequencies. Specifically, there is a need for magnetic thin films with ferromagnetic resonance frequencies ( f r ) in the range of several gigahertz. Nanogranular CoZrO thin films have emerged as promising candidates due to their high f r and high electrical resistivity. We fabricated CoZrO thin films using facing targets reactive sputtering with oxygen as the reactive gas. As the oxygen partial pressure ratio ( P O2 ) was gradually increased up to 0.8%, clear uniaxial magnetic anisotropy appeared, leading to improved soft magnetic properties. At a P O2 of 0.8%, the film exhibited the most superior soft magnetic properties. With further increase in P O2 , magnetic loops implying a stripe magnetic-domain structure were obtained. In this P O2 range, phase separation was observed, along with a sharp increase in electrical resistivity. f r of the CoZrO film formed at P O2 = 0.8% was determined to be 3.2 GHz from high-frequency permeability measurement. We have confirmed the effectiveness of facing targets’ reactive sputtering in preparing CoZrO films with excellent soft magnetic properties.
{"title":"Fabrication and Characterization CoZrO Films Deposited by Facing Targets Reactive Sputtering for Micromagnetic Inductors","authors":"Honami Nitta;Yota Takamura;Tadayuki Kaneko;Shigeki Nakagawa","doi":"10.1109/LMAG.2023.3320495","DOIUrl":"10.1109/LMAG.2023.3320495","url":null,"abstract":"In recent years, there has been a strong demand for soft magnetic films suitable for high-frequency micromagnetic devices as power electronics circuits to operate at higher frequencies. Specifically, there is a need for magnetic thin films with ferromagnetic resonance frequencies (\u0000<italic>f</i>\u0000<sub>r</sub>\u0000) in the range of several gigahertz. Nanogranular CoZrO thin films have emerged as promising candidates due to their high \u0000<italic>f</i>\u0000<sub>r</sub>\u0000 and high electrical resistivity. We fabricated CoZrO thin films using facing targets reactive sputtering with oxygen as the reactive gas. As the oxygen partial pressure ratio (\u0000<italic>P</i>\u0000<sub>O2</sub>\u0000) was gradually increased up to 0.8%, clear uniaxial magnetic anisotropy appeared, leading to improved soft magnetic properties. At a \u0000<italic>P</i>\u0000<sub>O2</sub>\u0000 of 0.8%, the film exhibited the most superior soft magnetic properties. With further increase in \u0000<italic>P</i>\u0000<sub>O2</sub>\u0000, magnetic loops implying a stripe magnetic-domain structure were obtained. In this \u0000<italic>P</i>\u0000<sub>O2</sub>\u0000 range, phase separation was observed, along with a sharp increase in electrical resistivity. \u0000<italic>f</i>\u0000<sub>r</sub>\u0000 of the CoZrO film formed at \u0000<italic>P</i>\u0000<sub>O2</sub>\u0000 = 0.8% was determined to be 3.2 GHz from high-frequency permeability measurement. We have confirmed the effectiveness of facing targets’ reactive sputtering in preparing CoZrO films with excellent soft magnetic properties.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135838519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-27DOI: 10.1109/LMAG.2023.3319992
Rahnuma Rahman;Supriyo Bandyopadhyay
Probabilistic computing with binary stochastic neurons (BSNs) implemented with low-barrier magnets (LBMs) or zero-energy barrier nanoscale ferromagnets possessing in-plane magnetic anisotropy has emerged as an efficient paradigm for solving computationally hard problems. The fluctuating magnetization of an LBM at room temperature encodes a p-bit, which is the building block of a BSN. Its drawback, however, is that the dynamics of common (transition metal) ferromagnets are relatively slow, and, hence, the number of uncorrelated p-bits that can be generated per second—the so-called “flips per second” ( fps )—is insufficient, leading to slow computational speed in autonomous coprocessing with p-computers. Here, we show that a simple way to increase fps in LBMs is to replace commonly used ferromagnets (e.g., Co, Fe, and Ni), which have large saturation magnetization Ms , with a dilute magnetic semiconductor, such as GaMnAs with much smaller saturation magnetization. The smaller Ms reduces any residual energy barrier within an LBM and increases the fps significantly. It also offers other benefits, such as reduced dipole coupling between neighbors, resulting in larger density of uncorrelated p-bits for more processing power, and reduced device-to-device variation. All this provides a way to realize the hardware acceleration and energy efficiency promise of p-computers.
{"title":"Increasing Flips per Second and Speed of p-Computers by Using Dilute Magnetic Semiconductors","authors":"Rahnuma Rahman;Supriyo Bandyopadhyay","doi":"10.1109/LMAG.2023.3319992","DOIUrl":"https://doi.org/10.1109/LMAG.2023.3319992","url":null,"abstract":"Probabilistic computing with binary stochastic neurons (BSNs) implemented with low-barrier magnets (LBMs) or zero-energy barrier nanoscale ferromagnets possessing in-plane magnetic anisotropy has emerged as an efficient paradigm for solving computationally hard problems. The fluctuating magnetization of an LBM at room temperature encodes a p-bit, which is the building block of a BSN. Its drawback, however, is that the dynamics of common (transition metal) ferromagnets are relatively slow, and, hence, the number of uncorrelated p-bits that can be generated per second—the so-called “flips per second” (\u0000<italic>fps</i>\u0000)—is insufficient, leading to slow computational speed in autonomous coprocessing with p-computers. Here, we show that a simple way to increase \u0000<italic>fps</i>\u0000 in LBMs is to replace commonly used ferromagnets (e.g., Co, Fe, and Ni), which have large saturation magnetization \u0000<italic>M<sub>s</sub></i>\u0000, with a dilute magnetic semiconductor, such as GaMnAs with much smaller saturation magnetization. The smaller \u0000<italic>M<sub>s</sub></i>\u0000 reduces any residual energy barrier within an LBM and increases the \u0000<italic>fps</i>\u0000 significantly. It also offers other benefits, such as reduced dipole coupling between neighbors, resulting in larger density of uncorrelated p-bits for more processing power, and reduced device-to-device variation. All this provides a way to realize the hardware acceleration and energy efficiency promise of p-computers.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-4"},"PeriodicalIF":1.2,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67763009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-26DOI: 10.1109/LMAG.2023.3319289
Guannan Wei;Rajasree Das;Daniel Lordan;Marek Lorenc;Barry Clark;David P. F. Hurley;Mike Hayes;Cian O'Mathuna;Ranajit Sai;Paul McCloskey
Soft magnetic properties of thin films for use as a core material are critical for the realization of future miniaturized electromagnetic devices operating at frequencies of tens or hundreds of megahertz. Laminated stacks consisting of alternate thin layers of magnetic material and dielectric material are widely used to suppress eddy current losses that dominate, especially at a higher frequency of operation. Thus, identifying a suitable dielectric layer, its optimum thickness, and the understanding of its effect on the performance of the laminated core is important. In this letter, six different CoZrTaB (CZTB) laminated cores are reported, featuring a variety of dielectric materials (AlN, SiN, Al 2 O 3 , and oxide CZTB) and/or dielectric thickness (5, 15, and 50 nm). This study shows that stacks with different dielectric materials have a varied residual stress that plays an important role in inducing magnetic anisotropy, thus affecting the permeability. CZTB stacks with oxide CZTB dielectric show the best combination of high permeability, low coercivity, and low losses at high frequency.
{"title":"Investigation of the Soft-Magnetic Properties of CoZrTaB Laminated Cores by Dielectric Layer Tuning","authors":"Guannan Wei;Rajasree Das;Daniel Lordan;Marek Lorenc;Barry Clark;David P. F. Hurley;Mike Hayes;Cian O'Mathuna;Ranajit Sai;Paul McCloskey","doi":"10.1109/LMAG.2023.3319289","DOIUrl":"https://doi.org/10.1109/LMAG.2023.3319289","url":null,"abstract":"Soft magnetic properties of thin films for use as a core material are critical for the realization of future miniaturized electromagnetic devices operating at frequencies of tens or hundreds of megahertz. Laminated stacks consisting of alternate thin layers of magnetic material and dielectric material are widely used to suppress eddy current losses that dominate, especially at a higher frequency of operation. Thus, identifying a suitable dielectric layer, its optimum thickness, and the understanding of its effect on the performance of the laminated core is important. In this letter, six different CoZrTaB (CZTB) laminated cores are reported, featuring a variety of dielectric materials (AlN, SiN, Al\u0000<sub>2</sub>\u0000O\u0000<sub>3</sub>\u0000, and oxide CZTB) and/or dielectric thickness (5, 15, and 50 nm). This study shows that stacks with different dielectric materials have a varied residual stress that plays an important role in inducing magnetic anisotropy, thus affecting the permeability. CZTB stacks with oxide CZTB dielectric show the best combination of high permeability, low coercivity, and low losses at high frequency.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2023-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67763016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Magnetic materials with low magnetic loss are required to realize both a high-frequency support and a miniaturization of radio frequency components. Hexagonal close-packed cobalt (hcp-Co) nanoparticles are considered suitable for high frequencies due to their nanoparticle morphology and high magnetocrystalline anisotropy. However, the face-centered cubic (fcc) or the ϵ phase with low magnetocrystalline anisotropy is fabricated in the synthetization of Co nanoparticles with a size of less than a few hundred nanometers. In this letter, we investigate the synthesis of Co nanoparticles by the thermolysis of dicobalt octacarbonyl at various temperatures for obtaining Co particles with a single hcp phase. Although Co nanoparticles synthesized at 453 K exhibited a mixture of hcp and fcc phases with an hcp phase ratio of 25%, Co nanoparticles almost achieved the hcp phase ratio of 100% by decreasing the thermolysis temperature to 333 K or lower. Furthermore, we evaluated the permeability spectrum of the composite with Co particles of 10 vol% dispersed in polystyrene. Although the real part of the permeability in the composite containing Co nanoparticles with the mixed phase of fcc and hcp monotonously decreased with frequency, the composite contained Co nanoparticles with a single phase with a suitable constant value up to 3 GHz for high-frequency applications.
{"title":"Synthesis of Hexagonal Close-Packed Cobalt Nanoparticles From Thermolysis of Cobalt Carbonyl","authors":"Kyohei Takahashi;Hiroshi Ito;Isao Kanada;Hiroyuki Matsumoto","doi":"10.1109/LMAG.2023.3316608","DOIUrl":"https://doi.org/10.1109/LMAG.2023.3316608","url":null,"abstract":"Magnetic materials with low magnetic loss are required to realize both a high-frequency support and a miniaturization of radio frequency components. Hexagonal close-packed cobalt (hcp-Co) nanoparticles are considered suitable for high frequencies due to their nanoparticle morphology and high magnetocrystalline anisotropy. However, the face-centered cubic (fcc) or the ϵ phase with low magnetocrystalline anisotropy is fabricated in the synthetization of Co nanoparticles with a size of less than a few hundred nanometers. In this letter, we investigate the synthesis of Co nanoparticles by the thermolysis of dicobalt octacarbonyl at various temperatures for obtaining Co particles with a single hcp phase. Although Co nanoparticles synthesized at 453 K exhibited a mixture of hcp and fcc phases with an hcp phase ratio of 25%, Co nanoparticles almost achieved the hcp phase ratio of 100% by decreasing the thermolysis temperature to 333 K or lower. Furthermore, we evaluated the permeability spectrum of the composite with Co particles of 10 vol% dispersed in polystyrene. Although the real part of the permeability in the composite containing Co nanoparticles with the mixed phase of fcc and hcp monotonously decreased with frequency, the composite contained Co nanoparticles with a single phase with a suitable constant value up to 3 GHz for high-frequency applications.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-4"},"PeriodicalIF":1.2,"publicationDate":"2023-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67763015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This letter presents an innovative method for rapid and precise measurement of bacteria in liquid samples for point-of-care testing. The method utilizes the bacteria concentration-dependent ac susceptibility of magnetic nanoparticles, allowing for efficient and practical bacterial detection. The ac susceptibility of the magnetic nanoparticles/bacteria aggregate exhibits a decrease proportional to the bacteria concentration, attributed to the influence of bacteria on the magnetic coupling between the magnetic nanoparticles and magnetic dynamic response of the aggregate. To validate the performance of our method, we conducted measurements on Fusobacterium nucleatum samples obtained from both healthy individuals and cancer patients. The results demonstrated a robust correlation (correlation factor up to 0.94) between our measurements and the results obtained through quantitative polymerase chain reaction (qPCR) analysis, highlighting the high precision and accuracy of our method in quantifying bacteria, which is comparable to a qPCR system. The simplified apparatus not only reduces costs but also saves time by eliminating the need for DNA amplification of short segments, making it a promising alternative for rapid and precise bacterial measurement in point-of-care testing.
{"title":"Magnetic Susceptibility-Based Detection of Fusobacterium Nucleatum in Human Saliva","authors":"Kazuhiko Okita;Youcheng Pu;Loi Tonthat;Toru Murayama;Shin Yabukami;Yohei Ozawa;Seji Asamitsu;Hiroshi Okamoto;Takashi Kamei","doi":"10.1109/LMAG.2023.3308062","DOIUrl":"https://doi.org/10.1109/LMAG.2023.3308062","url":null,"abstract":"This letter presents an innovative method for rapid and precise measurement of bacteria in liquid samples for point-of-care testing. The method utilizes the bacteria concentration-dependent ac susceptibility of magnetic nanoparticles, allowing for efficient and practical bacterial detection. The ac susceptibility of the magnetic nanoparticles/bacteria aggregate exhibits a decrease proportional to the bacteria concentration, attributed to the influence of bacteria on the magnetic coupling between the magnetic nanoparticles and magnetic dynamic response of the aggregate. To validate the performance of our method, we conducted measurements on \u0000<italic>Fusobacterium nucleatum</i>\u0000 samples obtained from both healthy individuals and cancer patients. The results demonstrated a robust correlation (correlation factor up to 0.94) between our measurements and the results obtained through quantitative polymerase chain reaction (qPCR) analysis, highlighting the high precision and accuracy of our method in quantifying bacteria, which is comparable to a qPCR system. The simplified apparatus not only reduces costs but also saves time by eliminating the need for DNA amplification of short segments, making it a promising alternative for rapid and precise bacterial measurement in point-of-care testing.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-4"},"PeriodicalIF":1.2,"publicationDate":"2023-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67763007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-22DOI: 10.1109/LMAG.2023.3307296
Qiangxin Li;Jian Feng;Qi Xiao;Xiong Gao
The lowest order mode of a shear-horizontal electromagnetic acoustic transducer (EMAT) typically exhibits a low signal-to-noise ratio and poor spatial resolution in defect detection. To solve this issue, this letter presents a crack identification and location method based on dual-reception magnetic encoded spatial pulse compression technology. On the one hand, the method implements spatial pulse compression technology by adjusting the spatial distribution of the magnetic field to obtain a high amplitude and narrow pulse detection signal. On the other hand, this method multiplexes the excitation EMAT as a receiver through signal processing technology, so that the position of cracks can be more accurately judged by analyzing the signals of the dual EMATs. Most importantly, this method does not require additional EMAT and complex excitation equipment. Finally, a simulation model was built to verify the method. The simulation results show, that compared with the detection signal of the traditional method, the SNR is improved by over 1.1 dB, and the spatial resolution is improved by over 18%. Additionally, the method can effectively distinguish the crack defects on both sides of EMATs, and the localization accuracy exceeds 95%.
{"title":"A Method of Shear-Horizontal EMAT Based on Dual-Reception Magnetic Encoded Spatial Pulse Compression for Multiple Cracks Identification and Location","authors":"Qiangxin Li;Jian Feng;Qi Xiao;Xiong Gao","doi":"10.1109/LMAG.2023.3307296","DOIUrl":"https://doi.org/10.1109/LMAG.2023.3307296","url":null,"abstract":"The lowest order mode of a shear-horizontal electromagnetic acoustic transducer (EMAT) typically exhibits a low signal-to-noise ratio and poor spatial resolution in defect detection. To solve this issue, this letter presents a crack identification and location method based on dual-reception magnetic encoded spatial pulse compression technology. On the one hand, the method implements spatial pulse compression technology by adjusting the spatial distribution of the magnetic field to obtain a high amplitude and narrow pulse detection signal. On the other hand, this method multiplexes the excitation EMAT as a receiver through signal processing technology, so that the position of cracks can be more accurately judged by analyzing the signals of the dual EMATs. Most importantly, this method does not require additional EMAT and complex excitation equipment. Finally, a simulation model was built to verify the method. The simulation results show, that compared with the detection signal of the traditional method, the SNR is improved by over 1.1 dB, and the spatial resolution is improved by over 18%. Additionally, the method can effectively distinguish the crack defects on both sides of EMATs, and the localization accuracy exceeds 95%.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2023-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67762114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-02DOI: 10.1109/LMAG.2023.3301384
Seyed Hassan Hadi Nemati;Nima Eslami;Mohammad Hossein Moaiyeri
The computing-in-memory (CiM) approach is a promising option for addressing the processor–memory data transfer bottleneck while performing data-intensive applications. In this letter, we present a novel CiM architecture based on spin-transfer torque magnetic random-access memory, which can work in computing and memory modes. In this letter, two spintronic devices are considered per cell to store the main data and its complement to address the reliability concerns during the read operation, which also provides a fascinating ability for performing reliable Boolean operations (all basic functions), binary/ternary content-addressable memory search operation, and multi-input majority function. Since the developed architecture can perform bitwise xnor operations in one cycle, a resistive-based accumulator has been designed to perform multi-input majority production to improve the structure for implementing fast and low-cost binary neural networks (BNNs). To this end, multiplication, accumulation, and passing through the activation function are accomplished in three cycles. The simulation result of exploiting the architecture in the BNN application indicates 86%–98% lower power-delay product than existing architectures.
{"title":"Computing in Memory Using Doubled STT-MRAM With the Application of Binarized Neural Networks","authors":"Seyed Hassan Hadi Nemati;Nima Eslami;Mohammad Hossein Moaiyeri","doi":"10.1109/LMAG.2023.3301384","DOIUrl":"https://doi.org/10.1109/LMAG.2023.3301384","url":null,"abstract":"The computing-in-memory (CiM) approach is a promising option for addressing the processor–memory data transfer bottleneck while performing data-intensive applications. In this letter, we present a novel CiM architecture based on spin-transfer torque magnetic random-access memory, which can work in computing and memory modes. In this letter, two spintronic devices are considered per cell to store the main data and its complement to address the reliability concerns during the read operation, which also provides a fascinating ability for performing reliable Boolean operations (all basic functions), binary/ternary content-addressable memory search operation, and multi-input majority function. Since the developed architecture can perform bitwise \u0000<sc>xnor</small>\u0000 operations in one cycle, a resistive-based accumulator has been designed to perform multi-input majority production to improve the structure for implementing fast and low-cost binary neural networks (BNNs). To this end, multiplication, accumulation, and passing through the activation function are accomplished in three cycles. The simulation result of exploiting the architecture in the BNN application indicates 86%–98% lower power-delay product than existing architectures.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2023-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67919308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-13DOI: 10.1109/LMAG.2023.3295271
Sohom Bhattacharjee;Choon Sik Cho;Dong Sik Cho
Transcranial magnetic stimulation (TMS) is a noninvasive neuromodulation technique that is used to treat a variety of neurological disorders, including major depression. The development of the deep brain TMS coil for stimulating subcortical structures expands the use of TMS beyond the stimulation of superficial cortical targets. Deep brain stimulation may have beneficial effects on neurological disorders such as Parkinson's disease, post-traumatic stress disorder, and mild traumatic brain injury. Previous studies have shown that the cerebellum plays a very big role in behavior and motor planning. To stimulate the specific areas of the human brain, we require a TMS coil with precise focal abilities because the material, design, and position of a TMS coil play a significant role in adjusting the coil's focusing power. Therefore, we studied stimulation of the frontal brain and cerebellum with two different new coil designs positioned on different locations. A rare design of the TMS coil made with Litz wire was developed to enhance excitation focality in the brain and was compared with a traditional figure-of-eight (FOE) coil and double-cone coil. The finite-element simulation tool ANSYS Maxwell 3-D has been used to simulate and compare the magnetic field and electric field induced inside the model of the human brain. The coil studies are as follows: a FOE coil, an overlapped copper coil, and a Litz wire overlapped coil. This was followed by experimental validation which shows great agreement with the simulation results.
{"title":"Development of Overlapped Designed Coils for Transcranial Magnetic Stimulations","authors":"Sohom Bhattacharjee;Choon Sik Cho;Dong Sik Cho","doi":"10.1109/LMAG.2023.3295271","DOIUrl":"https://doi.org/10.1109/LMAG.2023.3295271","url":null,"abstract":"Transcranial magnetic stimulation (TMS) is a noninvasive neuromodulation technique that is used to treat a variety of neurological disorders, including major depression. The development of the deep brain TMS coil for stimulating subcortical structures expands the use of TMS beyond the stimulation of superficial cortical targets. Deep brain stimulation may have beneficial effects on neurological disorders such as Parkinson's disease, post-traumatic stress disorder, and mild traumatic brain injury. Previous studies have shown that the cerebellum plays a very big role in behavior and motor planning. To stimulate the specific areas of the human brain, we require a TMS coil with precise focal abilities because the material, design, and position of a TMS coil play a significant role in adjusting the coil's focusing power. Therefore, we studied stimulation of the frontal brain and cerebellum with two different new coil designs positioned on different locations. A rare design of the TMS coil made with Litz wire was developed to enhance excitation focality in the brain and was compared with a traditional figure-of-eight (FOE) coil and double-cone coil. The finite-element simulation tool ANSYS Maxwell 3-D has been used to simulate and compare the magnetic field and electric field induced inside the model of the human brain. The coil studies are as follows: a FOE coil, an overlapped copper coil, and a Litz wire overlapped coil. This was followed by experimental validation which shows great agreement with the simulation results.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67762070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this letter, we present a 1T1D1M-based (one transistor, one diode, and one magnetic tunnel junction) spin-orbit torque, magnetic random-access memory (SOT-MRAM) with multimode magnetization switching for high-density memory, ultrahigh-speed writing, and energy-efficient on-chip memory application. The conventional spin-transfer torque (STT)-MRAM or SOT-MRAM is limited by the unipolar (or bipolar) switching property and demands the utilization of a common channel with bidirectional write current, which not only brings about source degradation of the access transistor but also increases the energy consumption in the write operation. By introducing a Schottky diode, the 1T1D1SOT-MRAM cell based on ultrafast switching of multiple modes outperforms conventional MRAMs in terms of decoupling of current channels in different directions and high-density integration. Simulation results show that the MRAM achieves 82% and 100% reduction in bit-cell area compared with STT-MRAM and SOT-MRAM, respectively, and ∼3.3× improvement in write energy consumption in comparison with STT-MRAM.
{"title":"High-Density 1T1D1SOT-MRAM With Multimode Ultrahigh-Speed Magnetization Switching","authors":"Hao Zhang;Di Wang;Long Liu;Xuefeng Zhao;Huai Lin;Changqing Xie","doi":"10.1109/LMAG.2023.3293407","DOIUrl":"https://doi.org/10.1109/LMAG.2023.3293407","url":null,"abstract":"In this letter, we present a 1T1D1M-based (one transistor, one diode, and one magnetic tunnel junction) spin-orbit torque, magnetic random-access memory (SOT-MRAM) with multimode magnetization switching for high-density memory, ultrahigh-speed writing, and energy-efficient on-chip memory application. The conventional spin-transfer torque (STT)-MRAM or SOT-MRAM is limited by the unipolar (or bipolar) switching property and demands the utilization of a common channel with bidirectional write current, which not only brings about source degradation of the access transistor but also increases the energy consumption in the write operation. By introducing a Schottky diode, the 1T1D1SOT-MRAM cell based on ultrafast switching of multiple modes outperforms conventional MRAMs in terms of decoupling of current channels in different directions and high-density integration. Simulation results show that the MRAM achieves 82% and 100% reduction in bit-cell area compared with STT-MRAM and SOT-MRAM, respectively, and ∼3.3× improvement in write energy consumption in comparison with STT-MRAM.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67763004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The effects of uniform and static moderate magnetic fields (0–400 mT) on the membrane potential of nerve fibers in Metapenaeus ensis shrimps were investigated. The results showed that the magnetic field caused an increase in membrane potential, eventually reaching a static state, and that effects of short-term exposure were largely reversible. A nonlinear relationship between the percentage change in membrane potential ( V% ) and magnetic field induction was observed, where V% increased rapidly below an inflection point (around 200 mT) and slowed down thereafter. Hypotheses suggest that ion channels in the membrane have varying sensitivities to magnetic fields and presented the distribution of ion channel activation thresholds within the 0–400 mT range. The identification of the inflection point holds great practical value in the fields of magnetic field therapy, exposure limits, and magnetic shielding design.
{"title":"Effect of Moderate Static Magnetic Field on Membrane Potential of Abdominal Nerve Fiber in Metapenaeus Ensis","authors":"Siyuan Liu;Shupeng Liu;Yongyong Gong;Jinbo Chen;Hengyu Li;Zhizheng Wu;Ze Cui;Mei Liu;Jingtao Lei;Tao Wang","doi":"10.1109/LMAG.2023.3293391","DOIUrl":"https://doi.org/10.1109/LMAG.2023.3293391","url":null,"abstract":"The effects of uniform and static moderate magnetic fields (0–400 mT) on the membrane potential of nerve fibers in \u0000<italic>Metapenaeus ensis</i>\u0000 shrimps were investigated. The results showed that the magnetic field caused an increase in membrane potential, eventually reaching a static state, and that effects of short-term exposure were largely reversible. A nonlinear relationship between the percentage change in membrane potential (\u0000<italic>V%</i>\u0000) and magnetic field induction was observed, where \u0000<italic>V%</i>\u0000 increased rapidly below an inflection point (around 200 mT) and slowed down thereafter. Hypotheses suggest that ion channels in the membrane have varying sensitivities to magnetic fields and presented the distribution of ion channel activation thresholds within the 0–400 mT range. The identification of the inflection point holds great practical value in the fields of magnetic field therapy, exposure limits, and magnetic shielding design.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67919307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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