IEEE Transactions on Magnetics最新文献

{"title":"Super Resolution Multi-target Localization Method for Overlapped Magnetic Anomaly Field","authors":"Wupeng Xie;Yaxin Mu;Luzhao Chen;Xin Liu;Zhongde Yu","doi":"10.1109/TMAG.2025.3577379","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3577379","url":null,"abstract":"Significant progress has been made in the isolated ferrous target localization based on magnetic anomaly field. However, localizing multiple nearby targets remains an ongoing challenge, especially in cases of overlapped magnetic anomaly fields. Here, we propose a super resolution multi-target localization method based on the normalized source strength (NSS) data. Multiple uniformly distributed magnetic dipoles are preset in the solution space, so the measured NSS is the is the sum of the NSS generated by all magnetic dipoles, and an underdetermined linear system is established for the unknown vector of magnitude of magnetic moment of all diploes. Since the targets are sparse in the solution domain, <inline-formula> <tex-math>$L1$ </tex-math></inline-formula>-minimization technique is used to estimate the nonzero dipoles, thereby determining the number and position of the targets. Experiments and results have been demonstrated, indicating the target resolution is the interval of the magnetic dipoles in subsurface space, which is smaller than the spatial resolution of the magnetic anomaly field, and when the magnetic anomaly field is aliased, the proposed approach is able to estimate the number, position, and magnetic moment of the targets.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 8","pages":"1-5"},"PeriodicalIF":2.1,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144716242","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}

{"title":"Analytical Maximum Energy Product (BH)max Model for Rare-Earth-Free Magnets: Core–Shell Nanostructure","authors":"Yang-Ki Hong;Seok Bae;Jihoon Park;Minyeong Choi;Won-Cheol Lee;Chang-Dong Yeo;Md Abdul Wahed;Kisuk Lee;Haein Yim-Choi;Woo-Young Lee","doi":"10.1109/TMAG.2025.3576933","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3576933","url":null,"abstract":"This article presents an analytical model for the maximum energy product [<inline-formula> <tex-math>$(BH)_{max }$ </tex-math></inline-formula>] in core–shell structured magnetic exchange-coupled nanomagnets. The model was validated by comparing its results to the <inline-formula> <tex-math>$(BH)_{max }$ </tex-math></inline-formula> from core–shell magnets reported in the literature. This approach can serve as a universal model for designing core–shell magnets that achieve the desired <inline-formula> <tex-math>$(BH)_{max }$ </tex-math></inline-formula>. The <inline-formula> <tex-math>$(BH)_{max }$ </tex-math></inline-formula> was determined under two distinct nucleation field (<inline-formula> <tex-math>$H_{mathrm {N}}$ </tex-math></inline-formula>) conditions: <inline-formula> <tex-math>$H_{mathrm {N}} le M_{mathrm {r}}$ </tex-math></inline-formula>/2 and <inline-formula> <tex-math>$H_{mathrm {N}} ge M_{mathrm {r}}$ </tex-math></inline-formula>/2, where <inline-formula> <tex-math>$M_{mathrm {r}}$ </tex-math></inline-formula> is the remanent magnetization. In addition, two different values of magnetic hysteresis loop squareness (SQ <inline-formula> <tex-math>$= M_{mathrm {r}}$ </tex-math></inline-formula>/<inline-formula> <tex-math>$M_{mathrm {S}}$ </tex-math></inline-formula>) were used: 1.0 and 0.7. The soft magnetic shell’s remanent magnetic flux density (<inline-formula> <tex-math>$B_{mathrm {r}}$ </tex-math></inline-formula>) ranged from 0.7 to 2.2 T, while the core diameter (<inline-formula> <tex-math>$D_{mathrm {h}}$ </tex-math></inline-formula>) varied between 50 and 250 nm in this <inline-formula> <tex-math>$(BH)_{max }$ </tex-math></inline-formula> model. The low-temperature phase (LTP) MnBi-core/soft-shell nanomagnet can achieve a <inline-formula> <tex-math>$(BH)_{max }$ </tex-math></inline-formula> of 40 MGOe at a <inline-formula> <tex-math>$B_{mathrm {r}}$ </tex-math></inline-formula> of 1.6 T, with a shell thickness (<inline-formula> <tex-math>$delta _{mathrm {S}}$ </tex-math></inline-formula>) of 40 nm, a <inline-formula> <tex-math>$D_{mathrm {h}}$ </tex-math></inline-formula> of 250 nm, and a volume fraction of the hard-core (<inline-formula> <tex-math>$f_{mathrm {h}}$ </tex-math></inline-formula>) of 0.43. The <inline-formula> <tex-math>$(BH)_{max }$ </tex-math></inline-formula> of the hexaferrite (SrFe12O19)/soft-shell (1.9 T) nanomagnet can be improved from 5.8 (single hexaferrite phase) to 20 MGOe. This approach achieves the desired <inline-formula> <tex-math>$(BH)_{max }$ </tex-math></inline-formula> of the rare-earth(RE)-free permanent magnet, thereby tackling issues related to RE mineral security and unstable supply chains.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 9","pages":"1-9"},"PeriodicalIF":1.9,"publicationDate":"2025-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144909205","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}

{"title":"Effects of Winding Lorentz Force and Winding Structure on Shunt Reactor Core Vibration","authors":"Qili Lin;Runyu Liu;Mingzhu Xu;Guoqing Di","doi":"10.1109/TMAG.2025.3576032","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3576032","url":null,"abstract":"In previous simulation studies on reactor vibration, the influence of the winding Lorentz force (LF) has not been accurately quantified, and the effect of the winding structure has rarely been considered. This study addresses these gaps by developing a coupled electromagnetic-mechanical simulation model for a shunt reactor, incorporating both the Maxwell forces (MFs) on the core surface and the LFs of the winding. Using this model, the magnetic flux density and force distributions of the core and winding were compared, and the impacts of the winding LF and winding structure on core vibration were systematically analyzed. The results demonstrate that the MFs on the core surface are markedly larger than the LFs of the winding. The winding LF has a negligible influence on core displacement and vibration amplitude, with relative errors of less than 2% when the LF is excluded from the model. In contrast, while the winding structure has a minimal effect on the peak displacement of the core, it notably affects the vibration amplitude, particularly at the frequency of 100 Hz. Modal analysis further reveals that the absence of the winding structure leads to a substantial reduction in the core’s axial natural frequency. This highlights the winding structure as a critical factor in reactor vibration simulations. The findings of this study provide valuable insights for advancing reactor vibration analysis and control strategies while also highlighting the critical importance of accurately modeling both electromagnetic and structural interactions in future research.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 7","pages":"1-8"},"PeriodicalIF":2.1,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144536454","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}

{"title":"The Improvement of High-Frequency Performances and the Inductance of Micro-Inductors by Tuning the B-Gradient in Composition Gradient Sputtered FeCoB Thin Films","authors":"Dalong Qiu;Xiaosong Wang;Shipeng Zhang;Wencai Lv;Shuguang Yi;Ming Liu;Yifei Zhang;Shandong Li","doi":"10.1109/TMAG.2025.3575406","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3575406","url":null,"abstract":"The static and dynamic magnetic properties of 50 nm thick iron-cobalt-boron (FeCoB) soft magnetic films, fabricated using a composition gradient sputtering (CGS) method on intrinsic Si (100) substrates, are studied as a function of the B composition gradient. By optimizing the B composition gradient, larger stress is induced, resulting in an increase of the uniaxial magnetic anisotropy field <inline-formula> <tex-math>${H} _{k}$ </tex-math></inline-formula> from 229.7 to 720.1 Oe and an increase in ferromagnetic resonance (FMR) frequency from 5.8 to 9.27 GHz. These are attributed to the B doping, which eliminated magneto-crystalline anisotropy, with the stress induced by the composition gradient becoming the dominant factor. The film was then integrated as a magnetic core into a planar spiral inductor, resulting in a 24.6% increase in inductance, demonstrating the potential of this film as a material for magnetic cores in high-frequency electronic components.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 7","pages":"1-7"},"PeriodicalIF":2.1,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144536458","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}

{"title":"Multiscale Micromagnetic/Atomistic Modeling of Heat-Assisted Magnetic Recording","authors":"Mohammed Gija;Alexey Dobrynin;Kevin McNeill;Mark Gubbins;Tim Mercer;Philip Bissell;Serban Lepadatu","doi":"10.1109/TMAG.2025.3565885","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3565885","url":null,"abstract":"Heat-assisted magnetic recording (HAMR) is a recent advancement in magnetic recording, allowing for a significant increase in the areal density capability (ADC) of hard disk drives (HDDs) compared to the perpendicular magnetic recording (PMR) technology. This is enabled by high anisotropy FePt media, which needs to be heated through its Curie temperature (<inline-formula> <tex-math>$T_{C}$ </tex-math></inline-formula>) to facilitate magnetization reversal by an electromagnetic write pole. HAMR micromagnetic modeling is, therefore, challenging, as it needs to be performed in proximity to and above <inline-formula> <tex-math>$T_{C}$ </tex-math></inline-formula>, where a ferromagnet has no spontaneous magnetization. An atomistic model is an optimal solution here, as it does not require any parameter renormalization or non-physical assumptions for modeling at any temperature. However, a full-track atomistic recording model is extremely computationally expensive. Here, we demonstrate a true multiscale HAMR modeling approach, combining atomistic spin dynamics (ASD) modeling for high-temperature regions and micromagnetic modeling for lower-temperature regions, in a moving simulation window embedded within a long magnetic track. The advantages of this approach include the natural emergence of <inline-formula> <tex-math>$T_{C}$ </tex-math></inline-formula> and anisotropy distributions of FePt grains. Efficient GPU optimization of the code provides very fast running times, with a 60 nm wide track of 25 20 nm long bits being recorded in several hours on a single GPU. The effects of realistic FePt L10 versus simple cubic (SC) crystal structure are discussed, with the latter providing further running time gains while keeping the advantages of the multiscale approach.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 7","pages":"1-9"},"PeriodicalIF":2.1,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144536360","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}

{"title":"Ultrafast Switching and Selective Data Writing Through Voltage-Gated Spin-Orbit Torque in Perpendicular Magnetic Tunnel Junction Arrays","authors":"Haojie Zhang;Xinyuan Li;Zhaochun Liu;Jiahao Liu;Weixiang Li;Jiaqi Lu;Shiyang Lu;Danrong Xiong;Kaihua Cao;Shouzhong Peng","doi":"10.1109/TMAG.2025.3565284","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3565284","url":null,"abstract":"Spin-orbit torque magnetic random access memory (SOT-MRAM) exhibits substantial promise as a candidate for next-generation high-performance memory technologies. Ultrafast switching and high density are essential for the practical application of SOT-MRAM. In this article, we experimentally demonstrate spin-orbit torque (SOT) switching in W-based perpendicular magnetic tunnel junctions (MTJs) with a diameter of 80 nm. Our experiments show that W-based MTJs maintain reliable switching under nanosecond pulses. Dynamic switching experiments reveal that ultrafast switching with an incubation time of 0.3 ns and a switching time of 0.3 ns can be achieved. Furthermore, when a gate voltage of 1 V is applied, the SOT switching power consumption is reduced by 76% owing to the voltage-controlled magnetic anisotropy (VCMA) effect. Subsequently, we fabricate a memory array incorporating multiple MTJs on a shared W strip to improve storage density. Selective data writing within the MTJ array is demonstrated with voltage-gated SOT (VGSOT) switching, achieving a write error rate (WER) below <inline-formula> <tex-math>$6.7times 10^{-5}$ </tex-math></inline-formula>. These findings showcase the superior capabilities of VGSOT devices and emphasize their promising potential for magnetic random access memory (MRAM) applications.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 9","pages":"1-5"},"PeriodicalIF":1.9,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144920469","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}

{"title":"Direct Cooling of Stator End-Windings Using Ferrofluids: An Exploratory Experimental Study on Flow Dynamics and Heat Transfer","authors":"Manuel Rietz;Qiya Shu;Hakim El Bahi;Jonathan Raisin;Reinhold Kneer;Hossein Askarizadeh","doi":"10.1109/TMAG.2025.3564337","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3564337","url":null,"abstract":"Efficient cooling is essential for electrical machines working with high power density. Ferrofluids offer a high potential to be served as an efficient coolant. However, they have not yet been studied for cooling purposes in an impinging jet flow and in the presence of alternating magnetic fields. In such a configuration, the ferrofluid flow is highly responsive to the magnetic field, and this strong interaction can substantially improve the cooling process. Alternating magnetic fields are present around the motor coils of a stator. In this regard, an experimental setup is built to investigate the cooling performance of two configurations of ferrofluid jet impingement onto the end-winding of a single coil: 1) the horizontal jet configuration impinging perpendicularly onto the end-winding; and 2) the vertical jet configuration impinging on the top of the end-winding. Both configurations exhibit similar cooling performances indicating the more pronounced influence of the ferrofluid flow interaction with the magnetic field compared to the influence of the impingement direction. A promising improvement of the cooling performance (up to a doubling) is found if magnetic flux densities on the side of the end-winding becomes larger than 10 mT and the alternating frequencies are sufficiently small to stimulate strong interactions between the ferrofluid flow and the magnetic fields at the end-winding.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 7","pages":"1-10"},"PeriodicalIF":2.1,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144536456","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}

{"title":"IEEE Transactions on Magnetics Institutional Listings","authors":"","doi":"10.1109/TMAG.2025.3561647","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3561647","url":null,"abstract":"","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 5","pages":"C4-C4"},"PeriodicalIF":2.1,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10976470","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143871100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"IEEE Transactions on Magnetics Publication Information","authors":"","doi":"10.1109/TMAG.2025.3561645","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3561645","url":null,"abstract":"","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 5","pages":"C3-C3"},"PeriodicalIF":2.1,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10976374","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143871009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"IEEE Magnetics Society Information","authors":"","doi":"10.1109/TMAG.2025.3561641","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3561641","url":null,"abstract":"","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 5","pages":"C2-C2"},"PeriodicalIF":2.1,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10976465","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143870842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}