Pub Date : 2025-11-03DOI: 10.1109/TMAG.2025.3628061
Dávid Sivý;Jozef Strečka
We investigate the deformable quantum spin-1/2 XX chain in a transverse magnetic field, which is exactly solvable via the Jordan–Wigner transformation under the assumption of a linear dependence of the exchange interaction on uniform lattice distortion. By calculating the magnetization, magnetic susceptibility, distortion parameter, and inverse compressibility, we explore the coupled magnetic and elastic properties of the deformable quantum spin chain. It is demonstrated that the deformable spin-1/2 XX chain in a transverse magnetic field exhibits a line of discontinuous phase transitions emerging at low but finite temperatures, which terminates at a critical point corresponding to a continuous phase transition. The discontinuous thermal phase transitions are accompanied by magnetic hysteresis due to metastable states, which gradually vanishes as the temperature increases.
{"title":"Thermal Phase Transitions in a Deformable Quantum Spin-1/2 XX Chain in a Transverse Magnetic Field","authors":"Dávid Sivý;Jozef Strečka","doi":"10.1109/TMAG.2025.3628061","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3628061","url":null,"abstract":"We investigate the deformable quantum spin-1/2 XX chain in a transverse magnetic field, which is exactly solvable via the Jordan–Wigner transformation under the assumption of a linear dependence of the exchange interaction on uniform lattice distortion. By calculating the magnetization, magnetic susceptibility, distortion parameter, and inverse compressibility, we explore the coupled magnetic and elastic properties of the deformable quantum spin chain. It is demonstrated that the deformable spin-1/2 XX chain in a transverse magnetic field exhibits a line of discontinuous phase transitions emerging at low but finite temperatures, which terminates at a critical point corresponding to a continuous phase transition. The discontinuous thermal phase transitions are accompanied by magnetic hysteresis due to metastable states, which gradually vanishes as the temperature increases.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 12","pages":"1-4"},"PeriodicalIF":1.9,"publicationDate":"2025-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145600672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-31DOI: 10.1109/TMAG.2025.3627652
Kyoung-Min Kim;Myeong-Hwan Hwang;Eugene Kim;Hyun-Rok Cha
This article presents an arc-shaped rotor-notch topology for reducing cogging torque in axial flux permanent magnet (AFPM) motors. Unlike traditional techniques such as magnet skewing or segmentation, which often increase manufacturing complexity, the proposed notch enables localized flux attenuation without altering the stator or magnet volume. By aligning the notch with high-flux-density regions beneath the magnet edge, the design passively modulates magnetic energy and suppresses cogging torque. To evaluate the effectiveness of the proposed notch geometry, we propose a geometry-sensitive analytical indicator that combines magnetic field strength with flux attenuation efficiency. This indicator serves as a theoretical tool to guide notch design and is shown to correlate well with finite element analysis (FEA) and experimental results, including a 27.5% reduction in cogging torque and only a 5.4% decrease in average torque. This approach offers a simple, cost-effective, and scalable solution for cogging torque suppression without compromising performance or manufacturability. It is especially suitable for AFPM drives employing bobbin-inserted windings, where wider slot openings tend to amplify cogging torque. This insight offers a new strategy for geometry-driven rotor design optimization in precision electric mobility systems.
{"title":"Cogging Torque Reduction in Axial Flux Permanent Magnet Motor Using Arc-Notched Rotor: Design and Experimental Validation","authors":"Kyoung-Min Kim;Myeong-Hwan Hwang;Eugene Kim;Hyun-Rok Cha","doi":"10.1109/TMAG.2025.3627652","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3627652","url":null,"abstract":"This article presents an arc-shaped rotor-notch topology for reducing cogging torque in axial flux permanent magnet (AFPM) motors. Unlike traditional techniques such as magnet skewing or segmentation, which often increase manufacturing complexity, the proposed notch enables localized flux attenuation without altering the stator or magnet volume. By aligning the notch with high-flux-density regions beneath the magnet edge, the design passively modulates magnetic energy and suppresses cogging torque. To evaluate the effectiveness of the proposed notch geometry, we propose a geometry-sensitive analytical indicator that combines magnetic field strength with flux attenuation efficiency. This indicator serves as a theoretical tool to guide notch design and is shown to correlate well with finite element analysis (FEA) and experimental results, including a 27.5% reduction in cogging torque and only a 5.4% decrease in average torque. This approach offers a simple, cost-effective, and scalable solution for cogging torque suppression without compromising performance or manufacturability. It is especially suitable for AFPM drives employing bobbin-inserted windings, where wider slot openings tend to amplify cogging torque. This insight offers a new strategy for geometry-driven rotor design optimization in precision electric mobility systems.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 12","pages":"1-15"},"PeriodicalIF":1.9,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145600696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-31DOI: 10.1109/TMAG.2025.3627674
Yiduan Chen;Yutong Zheng
This article presents a novel dual-stator hybrid multi-excitation flux-modulated machine (DS-HMFMM). The proposed machine employs symmetrically arranged alternating Halbach three-segment permanent magnets (Hal-PMs) and iron poles, which together form a “FeNFe–FeNFe” consequent-pole (CP) configuration. This design effectively concentrates the magnetic flux while minimizing flux leakage. The rotor features trapezoidal PMs (TPMs) embedded within a trapezoidal iron core, which aids in alleviating core saturation, thereby enhancing torque density and improving the utilization of PMs. Furthermore, the interaction between the rotor and stator iron poles modulates the magnetic field generated by the stator PMs, resulting in a bidirectional flux modulation effect that further amplifies torque output. The topology of the proposed DS-HMFMM is introduced, and its operational principles are elucidated based on a simplified magnetomotive force (MMF)-permeance model. Subsequently, an analysis is conducted to examine how pole–slot combinations and stator–rotor dimensions influence performance. To validate the advantages of the proposed DS-HMFMM, finite element analysis (FEA) and air-gap harmonic analysis are performed. A comparative study with traditional three-alternating-pole split-tooth PM Vernier machines (T-CPM STVM) is also presented. Finally, the id = 0 dual-loop field-oriented control (Dual-loop FOC) strategy was implemented in the DS-HMFMM} to evaluate its operational characteristics under various working conditions. The results demonstrate that, in comparison to conventional T-CPM} STVM designs, the proposed DS-HMFMM} achieves a 42% increase in torque density, maintains torque ripple within 3%, delivers a 37% improvement in output power, shows an efficiency enhancement of 2.7%, and exhibits superior dynamic performance.
{"title":"Design and Analysis of a New Dual-Stator Hybrid Multi-Field Modulation Machine With Trapezoidal PMs","authors":"Yiduan Chen;Yutong Zheng","doi":"10.1109/TMAG.2025.3627674","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3627674","url":null,"abstract":"This article presents a novel dual-stator hybrid multi-excitation flux-modulated machine (DS-HMFMM). The proposed machine employs symmetrically arranged alternating Halbach three-segment permanent magnets (Hal-PMs) and iron poles, which together form a “FeNFe–FeNFe” consequent-pole (CP) configuration. This design effectively concentrates the magnetic flux while minimizing flux leakage. The rotor features trapezoidal PMs (TPMs) embedded within a trapezoidal iron core, which aids in alleviating core saturation, thereby enhancing torque density and improving the utilization of PMs. Furthermore, the interaction between the rotor and stator iron poles modulates the magnetic field generated by the stator PMs, resulting in a bidirectional flux modulation effect that further amplifies torque output. The topology of the proposed DS-HMFMM is introduced, and its operational principles are elucidated based on a simplified magnetomotive force (MMF)-permeance model. Subsequently, an analysis is conducted to examine how pole–slot combinations and stator–rotor dimensions influence performance. To validate the advantages of the proposed DS-HMFMM, finite element analysis (FEA) and air-gap harmonic analysis are performed. A comparative study with traditional three-alternating-pole split-tooth PM Vernier machines (T-CPM STVM) is also presented. Finally, the id = 0 dual-loop field-oriented control (Dual-loop FOC) strategy was implemented in the DS-HMFMM} to evaluate its operational characteristics under various working conditions. The results demonstrate that, in comparison to conventional T-CPM} STVM designs, the proposed DS-HMFMM} achieves a 42% increase in torque density, maintains torque ripple within 3%, delivers a 37% improvement in output power, shows an efficiency enhancement of 2.7%, and exhibits superior dynamic performance.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 12","pages":"1-12"},"PeriodicalIF":1.9,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145600704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-30DOI: 10.1109/TMAG.2025.3626790
Yitong Yin;Chuanhui Cheng;Fengyu Kong;Weihong Yang;Xinyuan Lin;Shiqiang Yue;Anding Wang
!Fe-based nanocrystalline alloy cores with super-high effective permeability (<inline-formula> <tex-math>$mu_{e}$ </tex-math></inline-formula>) and low core loss (<inline-formula> <tex-math>$L_{c}$ </tex-math></inline-formula>) are increasingly used in various electrical devices, yet the dependencies of dynamic magnetic characteristics on servicing conditions are rarely studied. In this study, two <inline-formula> <tex-math>$mathrm{Fe}-mathrm{Si}-mathrm{B}-mathrm{Nb}-mathrm{Cu}$ </tex-math></inline-formula> nanocrystalline alloy cores subjected to annealing at different temperatures in a transverse magnetic field were systematically investigated. The <inline-formula> <tex-math>$L_{c}$ </tex-math></inline-formula>, magnetic induction intensity (<inline-formula> <tex-math>$B_{m}$ </tex-math></inline-formula>), coercivity (<inline-formula> <tex-math>$H_{c}$ </tex-math></inline-formula>), and <inline-formula> <tex-math>$mu_{e}$ </tex-math></inline-formula> of the distinct cores were tested under the simulated servicing conditions by means of dc and ac BH loop tracers and an impedance analyzer. It is found that the annealing temperature (<inline-formula> <tex-math>$T_{A}$ </tex-math></inline-formula>) under transverse magnetic field exhibits strong effects on the sensitivities to servicing temperature <inline-formula> <tex-math>$left(T_{s}right), B_{m}$ </tex-math></inline-formula>, and frequency <inline-formula> <tex-math>$(f)$ </tex-math></inline-formula>. The core annealed at 440°C transverse field annealing [(TFA)-400] shows a super-high <inline-formula> <tex-math>$mu_{e}$ </tex-math></inline-formula> of about <inline-formula> <tex-math>$5.6 times 10^{4}$ </tex-math></inline-formula> at 100 kHz, which decreases with increasing <inline-formula> <tex-math>$T_{s}$ </tex-math></inline-formula>. The TFA-360 core exhibits a lower <inline-formula> <tex-math>$mu_{e}$ </tex-math></inline-formula> at room temperature (RT) yet can be improved at the high <inline-formula> <tex-math>$T_{s}$ </tex-math></inline-formula>. The <inline-formula> <tex-math>$H_{c}$ </tex-math></inline-formula> of the TFA-440 core is much lower than that of the TFA-360 one, yet it increases with the increasing <inline-formula> <tex-math>$T_{s}$ </tex-math></inline-formula>. It is also found that the TFA-440 core exhibits lower <inline-formula> <tex-math>$L_{c}$ </tex-math></inline-formula> in large f and <inline-formula> <tex-math>$T_{s}$ </tex-math></inline-formula> ranges, and <inline-formula> <tex-math>$L_{c}$ </tex-math></inline-formula> of Fe-Si-B-Nb-Cu nanocrystalline alloy cores shows an excellent temperature stability. Sensitivity factors of <inline-formula> <tex-math>$f, B_{m}$ </tex-math></inline-formula>, and P coefficient were also evaluated using the Steinmetz equation for comparison to other cores. These results should be good experimental and theoretical references for future improvement of the magnetic performance of magnetic cores and for core selection according to s
！具有超高有效磁导率（$mu_{e}$）和低磁芯损耗（$L_{c}$）的铁基纳米晶合金磁芯越来越多地应用于各种电气器件中，但对动态磁特性与使用条件的依赖关系的研究很少。在本研究中，系统地研究了两个$mathrm{Fe}-mathrm{Si}-mathrm{B}-mathrm{Nb}-mathrm{Cu}$纳米晶合金芯在横向磁场中不同温度下的退火。利用直流和交流BH回路示踪仪和阻抗分析仪，在模拟服役条件下测试了不同铁芯的$L_{c}$、磁感应强度（$B_{m}$）、矫顽力（$H_{c}$）和$mu_{e}$。发现横向磁场下的退火温度（$T_{A}$）对服务温度$left(T_{s}right), B_{m}$和频率$(f)$的灵敏度有很强的影响。440℃横向场退火[(TFA)-400]的铁心在100 kHz时显示出超高$mu_{e}$，约为$5.6 times 10^{4}$，随着$T_{s}$的增大而减小。TFA-360核心在室温（RT）下表现出较低的$mu_{e}$，但在高$T_{s}$下可以改进。TFA-440内核的$H_{c}$远低于TFA-360内核，但随着$T_{s}$的增大而增大。TFA-440纳米晶合金芯在大f和$T_{s}$范围内表现出较低的$L_{c}$， Fe-Si-B-Nb-Cu纳米晶合金芯在$L_{c}$范围内表现出优异的温度稳定性。利用Steinmetz方程对$f, B_{m}$的敏感性因子和P系数进行了评价，并与其他岩心进行了比较。这些结果为今后提高磁芯的磁性能和电气工程师根据使用条件选择磁芯提供了良好的实验和理论参考。
{"title":"Dynamic Magnetic Characteristics and Their Dependences on Servicing Conditions of Fe-Based Nanocrystalline Alloy Cores Modulated via Transverse Magnetic Field Annealing","authors":"Yitong Yin;Chuanhui Cheng;Fengyu Kong;Weihong Yang;Xinyuan Lin;Shiqiang Yue;Anding Wang","doi":"10.1109/TMAG.2025.3626790","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3626790","url":null,"abstract":"!Fe-based nanocrystalline alloy cores with super-high effective permeability (<inline-formula> <tex-math>$mu_{e}$ </tex-math></inline-formula>) and low core loss (<inline-formula> <tex-math>$L_{c}$ </tex-math></inline-formula>) are increasingly used in various electrical devices, yet the dependencies of dynamic magnetic characteristics on servicing conditions are rarely studied. In this study, two <inline-formula> <tex-math>$mathrm{Fe}-mathrm{Si}-mathrm{B}-mathrm{Nb}-mathrm{Cu}$ </tex-math></inline-formula> nanocrystalline alloy cores subjected to annealing at different temperatures in a transverse magnetic field were systematically investigated. The <inline-formula> <tex-math>$L_{c}$ </tex-math></inline-formula>, magnetic induction intensity (<inline-formula> <tex-math>$B_{m}$ </tex-math></inline-formula>), coercivity (<inline-formula> <tex-math>$H_{c}$ </tex-math></inline-formula>), and <inline-formula> <tex-math>$mu_{e}$ </tex-math></inline-formula> of the distinct cores were tested under the simulated servicing conditions by means of dc and ac BH loop tracers and an impedance analyzer. It is found that the annealing temperature (<inline-formula> <tex-math>$T_{A}$ </tex-math></inline-formula>) under transverse magnetic field exhibits strong effects on the sensitivities to servicing temperature <inline-formula> <tex-math>$left(T_{s}right), B_{m}$ </tex-math></inline-formula>, and frequency <inline-formula> <tex-math>$(f)$ </tex-math></inline-formula>. The core annealed at 440°C transverse field annealing [(TFA)-400] shows a super-high <inline-formula> <tex-math>$mu_{e}$ </tex-math></inline-formula> of about <inline-formula> <tex-math>$5.6 times 10^{4}$ </tex-math></inline-formula> at 100 kHz, which decreases with increasing <inline-formula> <tex-math>$T_{s}$ </tex-math></inline-formula>. The TFA-360 core exhibits a lower <inline-formula> <tex-math>$mu_{e}$ </tex-math></inline-formula> at room temperature (RT) yet can be improved at the high <inline-formula> <tex-math>$T_{s}$ </tex-math></inline-formula>. The <inline-formula> <tex-math>$H_{c}$ </tex-math></inline-formula> of the TFA-440 core is much lower than that of the TFA-360 one, yet it increases with the increasing <inline-formula> <tex-math>$T_{s}$ </tex-math></inline-formula>. It is also found that the TFA-440 core exhibits lower <inline-formula> <tex-math>$L_{c}$ </tex-math></inline-formula> in large f and <inline-formula> <tex-math>$T_{s}$ </tex-math></inline-formula> ranges, and <inline-formula> <tex-math>$L_{c}$ </tex-math></inline-formula> of Fe-Si-B-Nb-Cu nanocrystalline alloy cores shows an excellent temperature stability. Sensitivity factors of <inline-formula> <tex-math>$f, B_{m}$ </tex-math></inline-formula>, and P coefficient were also evaluated using the Steinmetz equation for comparison to other cores. These results should be good experimental and theoretical references for future improvement of the magnetic performance of magnetic cores and for core selection according to s","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 12","pages":"1-8"},"PeriodicalIF":1.9,"publicationDate":"2025-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145600716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-30DOI: 10.1109/TMAG.2025.3627217
Dasom Ahn;Seongmin Ahn;Siyeol Lee;Taehui Na
In this article, we propose an magnetic random access memory (MRAM)-based analog process-in-memory (MPIM) architecture with ternary output. The proposed architecture can: 1) increase array efficiency by binarizing the input to 0 or 1 instead of −1 or 1; 2) avoid accuracy degradation by using current compensation circuit; and 3) reduce energy overhead via 3-bit downscaling. Simulation results using a two-layer perceptron demonstrate that the proposed MPIM achieves 90.3% inference accuracy on the MNIST dataset and a peak energy efficiency of 819.8 TOPS/W at 200 MHz.
{"title":"Area-Efficient/Low-Power MRAM-PIM Based on Crossbar Array Utilizing Ternary Output","authors":"Dasom Ahn;Seongmin Ahn;Siyeol Lee;Taehui Na","doi":"10.1109/TMAG.2025.3627217","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3627217","url":null,"abstract":"In this article, we propose an magnetic random access memory (MRAM)-based analog process-in-memory (MPIM) architecture with ternary output. The proposed architecture can: 1) increase array efficiency by binarizing the input to 0 or 1 instead of −1 or 1; 2) avoid accuracy degradation by using current compensation circuit; and 3) reduce energy overhead via 3-bit downscaling. Simulation results using a two-layer perceptron demonstrate that the proposed MPIM achieves 90.3% inference accuracy on the MNIST dataset and a peak energy efficiency of 819.8 TOPS/W at 200 MHz.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 12","pages":"1-9"},"PeriodicalIF":1.9,"publicationDate":"2025-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145600724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-28DOI: 10.1109/TMAG.2025.3626441
Dongmei Yin;Qinghua Lin;Xiaofang Kong;Gang Wan
Based on the finite element/boundary element coupling method, a 3-D numerical simulation model of the transient electromagnetic field of a railgun is established to simulate the diffusion of current and magnetic field on the shields with different material combinations in the bore, as well as the evolution process of the magnetic field in the shield's cavity. The sliding electrical contact is defined between the rails and armature in this model. Combining with the theoretical analysis methods, the time of magnetic field diffusion in different shielding materials is evaluated. The influence of shield materials and the form of pulse current on the shielding effectiveness of the shield is analyzed through the simulation model. In order to investigate the effect of magnetic-structural coupling on the shielding effectiveness of the shield, a magnetic-structural coupling simulation model of the railgun launching process is also set up based on the multi-field coupling principle. The results reveal that in the strong magnetic field of the bore, the shield made of copper material with higher conductivity can relatively and significantly prevent the diffusion of the magnetic field into the shield's cavity. So its shielding effect is relatively good. With different forms of pulse current, the dominant shielding mechanism will vary, resulting in differences in shielding effectiveness of shields in the bore. The distribution of the magnetic field on the shield with and without considering the magnetic-structural coupling is different, especially with the passage of time the difference is more obvious.
{"title":"Discussion of the Influence of Multiple Factors on the Shielding of Magnetic Field in the Railgun’s Bore","authors":"Dongmei Yin;Qinghua Lin;Xiaofang Kong;Gang Wan","doi":"10.1109/TMAG.2025.3626441","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3626441","url":null,"abstract":"Based on the finite element/boundary element coupling method, a 3-D numerical simulation model of the transient electromagnetic field of a railgun is established to simulate the diffusion of current and magnetic field on the shields with different material combinations in the bore, as well as the evolution process of the magnetic field in the shield's cavity. The sliding electrical contact is defined between the rails and armature in this model. Combining with the theoretical analysis methods, the time of magnetic field diffusion in different shielding materials is evaluated. The influence of shield materials and the form of pulse current on the shielding effectiveness of the shield is analyzed through the simulation model. In order to investigate the effect of magnetic-structural coupling on the shielding effectiveness of the shield, a magnetic-structural coupling simulation model of the railgun launching process is also set up based on the multi-field coupling principle. The results reveal that in the strong magnetic field of the bore, the shield made of copper material with higher conductivity can relatively and significantly prevent the diffusion of the magnetic field into the shield's cavity. So its shielding effect is relatively good. With different forms of pulse current, the dominant shielding mechanism will vary, resulting in differences in shielding effectiveness of shields in the bore. The distribution of the magnetic field on the shield with and without considering the magnetic-structural coupling is different, especially with the passage of time the difference is more obvious.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 12","pages":"1-14"},"PeriodicalIF":1.9,"publicationDate":"2025-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145600725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-27DOI: 10.1109/TMAG.2025.3625608
Qianzhen Su;Zepeng Wang;Bo Zhang;Xiaolong Wen;Jianhua Li
Giant magnetoimpedance (GMI) sensors with off-diagonal mode have advantages of wide range, good linearity, and simple circuit. The performance of the sensor is directly affected by the number of turns of the signal pickup coil. In order to obtain amorphous wire GMI sensors with better performance, the number of turns of the signal pickup coil is usually larger. However, large pickup coils result in larger device size, which is not convenient to device miniaturization. In many conditions, small size device is needed. To achieve device miniaturization and keep the performance at the same time, increasing the cross-sectional area of the sensor is another choice. This article investigates the GMI sensor performance with varying amorphous wires. The aim is to provide a viable approach to enhance the sensor performance with miniaturized device size. We investigate the influence of the number of amorphous wires and coil turns on the performance of amorphous wire-based GMI sensors. The off-diagonal output responses of sensor with different numbers of wires were measured, and the output sensitivity and noise were compared for varying numbers of amorphous wires. The sensitivity of the sensor with a single amorphous wire is 85.23 mV/Oe, while that with eight amorphous wires reaches 266.36 mV/Oe. The noise level of the sensor with a single amorphous wire is 148.4 pT/rtHz@1 Hz, and the eight amorphous wires is 44.5 pT/rtHz@1 Hz. This work presents an approach to achieve a high-performance GMI sensor with less number of pickup coils.
{"title":"Enhanced Performance of Off-Diagonal GMI Magnetic Sensors by Using Optimized Amorphous Wire Array","authors":"Qianzhen Su;Zepeng Wang;Bo Zhang;Xiaolong Wen;Jianhua Li","doi":"10.1109/TMAG.2025.3625608","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3625608","url":null,"abstract":"Giant magnetoimpedance (GMI) sensors with off-diagonal mode have advantages of wide range, good linearity, and simple circuit. The performance of the sensor is directly affected by the number of turns of the signal pickup coil. In order to obtain amorphous wire GMI sensors with better performance, the number of turns of the signal pickup coil is usually larger. However, large pickup coils result in larger device size, which is not convenient to device miniaturization. In many conditions, small size device is needed. To achieve device miniaturization and keep the performance at the same time, increasing the cross-sectional area of the sensor is another choice. This article investigates the GMI sensor performance with varying amorphous wires. The aim is to provide a viable approach to enhance the sensor performance with miniaturized device size. We investigate the influence of the number of amorphous wires and coil turns on the performance of amorphous wire-based GMI sensors. The off-diagonal output responses of sensor with different numbers of wires were measured, and the output sensitivity and noise were compared for varying numbers of amorphous wires. The sensitivity of the sensor with a single amorphous wire is 85.23 mV/Oe, while that with eight amorphous wires reaches 266.36 mV/Oe. The noise level of the sensor with a single amorphous wire is 148.4 pT/rtHz@1 Hz, and the eight amorphous wires is 44.5 pT/rtHz@1 Hz. This work presents an approach to achieve a high-performance GMI sensor with less number of pickup coils.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 12","pages":"1-7"},"PeriodicalIF":1.9,"publicationDate":"2025-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145600713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-24DOI: 10.1109/TMAG.2025.3625386
Md Mahmudul Hasan;Richard Pasnak;Kelten Gonzales;Leszek M. Malkinski
Uniaxial anisotropy was induced in permalloy films deposited at room temperature at the magnetic field of 50 Oe. Films with induced helical anisotropy were deposited by rotating the magnetic field relative to the substrate during the deposition of subsequent layers. Isotropic films with the same thicknesses were deposited as a reference. Hysteresis loops of the samples with different types of anisotropy and different sizes of circular dot patterns were measured using a vibrating sample magnetometer. Results for the films deposited at the constant field are consistent with predictions of the Stoner–Wohlfarth model. Hysteresis loops of the samples with helical anisotropy markedly differ from those of isotropic samples. They have smaller coercivity, which decreases with the reduced size of the dots. The helical anisotropy seems to promote magnetization rotations, which lead to linear and almost nonhysteretic characteristics in circular patterns. The angular dependence of the magnetization at a fixed field displayed different characteristics for the fields rotated clockwise versus counterclockwise. The new method of inducing anisotropy is versatile and applies to any alloys, where pair-ordering results in magnetic anisotropy, and it is not limited to uniaxial or helical anisotropy. Potential applications target smooth switching in magnetoresistive random access memories (MRAMs), magneto-optical devices, and magnetic sensors.
{"title":"Induced Helical Anisotropy in Permalloy Thin Films and Patterns","authors":"Md Mahmudul Hasan;Richard Pasnak;Kelten Gonzales;Leszek M. Malkinski","doi":"10.1109/TMAG.2025.3625386","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3625386","url":null,"abstract":"Uniaxial anisotropy was induced in permalloy films deposited at room temperature at the magnetic field of 50 Oe. Films with induced helical anisotropy were deposited by rotating the magnetic field relative to the substrate during the deposition of subsequent layers. Isotropic films with the same thicknesses were deposited as a reference. Hysteresis loops of the samples with different types of anisotropy and different sizes of circular dot patterns were measured using a vibrating sample magnetometer. Results for the films deposited at the constant field are consistent with predictions of the Stoner–Wohlfarth model. Hysteresis loops of the samples with helical anisotropy markedly differ from those of isotropic samples. They have smaller coercivity, which decreases with the reduced size of the dots. The helical anisotropy seems to promote magnetization rotations, which lead to linear and almost nonhysteretic characteristics in circular patterns. The angular dependence of the magnetization at a fixed field displayed different characteristics for the fields rotated clockwise versus counterclockwise. The new method of inducing anisotropy is versatile and applies to any alloys, where pair-ordering results in magnetic anisotropy, and it is not limited to uniaxial or helical anisotropy. Potential applications target smooth switching in magnetoresistive random access memories (MRAMs), magneto-optical devices, and magnetic sensors.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 12","pages":"1-6"},"PeriodicalIF":1.9,"publicationDate":"2025-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145600726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-23DOI: 10.1109/TMAG.2025.3624210
Guntas Kaur;Tanmoy Pramanik
Micromagnetic modeling is employed to optimize the design of artificial synapse devices based on the spin-orbit-torque (SOT) driven domain wall (DW) motion along a nanotrack with triangular notches. Key attributes, such as the thermal stability of the pinned DW and depinning currents, are obtained for varied nanotrack geometries and pinning strength. Depinning probability as a function of SOT current density and pulsewidth is studied using finite temperature micromagnetic simulations for varying pinning potential. Results show that wider notches provide better thermal stability–depinning current tradeoff. On the other hand, narrow notches exhibit less variation in the depinning times at finite temperatures. It is observed that the DW position can be set precisely to any desired location by the SOT current pulse if the thermal stability is sufficiently high. The impact of shape variation and edge-roughness is also discussed. It is also observed that the metaplastic functionality can be realized by adding notches of progressively higher depinning currents along the nanotrack.
{"title":"Thermal Stability and Depinning Currents of Domain Wall-Based Artificial Synapses With Triangular Pinning Notches","authors":"Guntas Kaur;Tanmoy Pramanik","doi":"10.1109/TMAG.2025.3624210","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3624210","url":null,"abstract":"Micromagnetic modeling is employed to optimize the design of artificial synapse devices based on the spin-orbit-torque (SOT) driven domain wall (DW) motion along a nanotrack with triangular notches. Key attributes, such as the thermal stability of the pinned DW and depinning currents, are obtained for varied nanotrack geometries and pinning strength. Depinning probability as a function of SOT current density and pulsewidth is studied using finite temperature micromagnetic simulations for varying pinning potential. Results show that wider notches provide better thermal stability–depinning current tradeoff. On the other hand, narrow notches exhibit less variation in the depinning times at finite temperatures. It is observed that the DW position can be set precisely to any desired location by the SOT current pulse if the thermal stability is sufficiently high. The impact of shape variation and edge-roughness is also discussed. It is also observed that the metaplastic functionality can be realized by adding notches of progressively higher depinning currents along the nanotrack.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 12","pages":"1-8"},"PeriodicalIF":1.9,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145600664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-22DOI: 10.1109/TMAG.2025.3624005
Mohammad Asif;Prashant Kumar;Mirza Tariq Beg;M. Nizamuddin;Bijoy Kumar Kuanr
Single-layer Fe80Co20 and bilayers Ta/Fe80Co20 thin films are deposited on Si/SiO2 substrate using radio frequency (RF) magnetron sputtering. In this investigation, we systematically explore the impact of 5 nm thick Ta buffer layer and the thickness variation of Fe80Co20 films on their structural and magnetic properties. The magnetization relaxation of single-layer films deteriorates due to surface/interface roughness and defects, which cause the ferromagnetic resonance (FMR) line-widths ($boldsymbol{Delta} boldsymbol{H}$ ) to increase in comparison to bilayer Ta/Fe80Co20 thin films. We have evaluated and discussed how a 5 nm thick Ta buffer layer can reduce $Delta H$ and hence Gilbert damping ($alpha_{mathrm{eff}}$ ), due to the reduction in defect-induced two-magnon scattering (TMS) in comparison to FeCo films without a buffer layer. The value of $alpha_{text {eff }}$ reduced from $approx 7.4 times 10^{-3}$ to $approx 5.2 times 10^{-3}$ for 20 nm-thick FeCo films, without and with Ta buffer. The main contribution to the reduction in $alpha_{text {eff }}$ is attributed to a significant improvement in the surface morphology of Ta/Fe80Co20 thin films. In addition, we found that a Ta buffer layer significantly improves the static and dynamic properties of the ferromagnetic (FM) films. The saturation magnetization of the films with a Ta buffer was measured to be higher than films without buffer. Finally, we have designed, fabricated, and demonstrated microwave band-reject filters and phase shifters using the FeCo films in microstrip geometry. The band-stop filter has been tested experimentally from 7 to 20 GHz spanning in three microwave (C, X, and Ku) bands with a bias magnetic field up to ≈87.56 kA/m. The advantage of FeCo films with buffer layers has been demonstrated by much higher microwave attenuation (>23 dB). Similarly, in phase shifter application, we have obtained a differential phase shift greater than 105% cm in the film with a Ta buffer layer. These microwave applications are further verified by simulation through OOMME software.
采用射频磁控溅射技术在Si/SiO2衬底上沉积了单层Fe80Co20和双层Ta/Fe80Co20薄膜。在本研究中，我们系统地探讨了5 nm厚的Ta缓冲层和Fe80Co20薄膜厚度变化对其结构和磁性能的影响。由于表面/界面粗糙度和缺陷，单层薄膜的磁化弛豫恶化，导致铁磁共振（FMR）线宽（$boldsymbol{Delta} boldsymbol{H}$）比双层Ta/Fe80Co20薄膜增加。我们已经评估并讨论了与没有缓冲层的FeCo薄膜相比，5nm厚的Ta缓冲层如何减少$Delta H$和Gilbert阻尼（$alpha_{mathrm{eff}}$），这是由于缺陷诱导的双磁振子散射（TMS）的减少。对于20 nm厚的FeCo薄膜，无论有无Ta缓冲液，$alpha_{text {eff }}$的值都从$approx 7.4 times 10^{-3}$降低到$approx 5.2 times 10^{-3}$。降低$alpha_{text {eff }}$的主要原因是Ta/Fe80Co20薄膜表面形貌的显著改善。此外，我们发现Ta缓冲层显著改善了铁磁（FM）薄膜的静态和动态性能。结果表明，含Ta缓冲膜的饱和磁化强度高于无Ta缓冲膜。最后，我们设计、制作并演示了微波带阻滤波器和移相器，使用微带几何形状的FeCo薄膜。该带阻滤波器在7 ～ 20 GHz的三个微波波段（C、X和Ku）进行了实验测试，偏置磁场高达≈87.56 kA/m。具有缓冲层的FeCo薄膜的优点已被证明具有更高的微波衰减（>23 dB）。同样，在移相器的应用中，我们得到了大于105的微分相移% cm in the film with a Ta buffer layer. These microwave applications are further verified by simulation through OOMME software.
{"title":"Effect of Thickness and Buffer Layer on Magnetization and Spin Dynamics of Ferromagnetic Heterostructure: Microwave Monolithic Device Functionality","authors":"Mohammad Asif;Prashant Kumar;Mirza Tariq Beg;M. Nizamuddin;Bijoy Kumar Kuanr","doi":"10.1109/TMAG.2025.3624005","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3624005","url":null,"abstract":"Single-layer Fe80Co20 and bilayers Ta/Fe80Co20 thin films are deposited on Si/SiO2 substrate using radio frequency (RF) magnetron sputtering. In this investigation, we systematically explore the impact of 5 nm thick Ta buffer layer and the thickness variation of Fe80Co20 films on their structural and magnetic properties. The magnetization relaxation of single-layer films deteriorates due to surface/interface roughness and defects, which cause the ferromagnetic resonance (FMR) line-widths (<inline-formula> <tex-math>$boldsymbol{Delta} boldsymbol{H}$ </tex-math></inline-formula>) to increase in comparison to bilayer Ta/Fe80Co20 thin films. We have evaluated and discussed how a 5 nm thick Ta buffer layer can reduce <inline-formula> <tex-math>$Delta H$ </tex-math></inline-formula> and hence Gilbert damping (<inline-formula> <tex-math>$alpha_{mathrm{eff}}$ </tex-math></inline-formula>), due to the reduction in defect-induced two-magnon scattering (TMS) in comparison to FeCo films without a buffer layer. The value of <inline-formula> <tex-math>$alpha_{text {eff }}$ </tex-math></inline-formula> reduced from <inline-formula> <tex-math>$approx 7.4 times 10^{-3}$ </tex-math></inline-formula> to <inline-formula> <tex-math>$approx 5.2 times 10^{-3}$ </tex-math></inline-formula> for 20 nm-thick FeCo films, without and with Ta buffer. The main contribution to the reduction in <inline-formula> <tex-math>$alpha_{text {eff }}$ </tex-math></inline-formula> is attributed to a significant improvement in the surface morphology of Ta/Fe80Co20 thin films. In addition, we found that a Ta buffer layer significantly improves the static and dynamic properties of the ferromagnetic (FM) films. The saturation magnetization of the films with a Ta buffer was measured to be higher than films without buffer. Finally, we have designed, fabricated, and demonstrated microwave band-reject filters and phase shifters using the FeCo films in microstrip geometry. The band-stop filter has been tested experimentally from 7 to 20 GHz spanning in three microwave (C, X, and Ku) bands with a bias magnetic field up to ≈87.56 kA/m. The advantage of FeCo films with buffer layers has been demonstrated by much higher microwave attenuation (>23 dB). Similarly, in phase shifter application, we have obtained a differential phase shift greater than 105% cm in the film with a Ta buffer layer. These microwave applications are further verified by simulation through OOMME software.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 12","pages":"1-8"},"PeriodicalIF":1.9,"publicationDate":"2025-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145600670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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