IEEE Magnetics Letters最新文献

{"title":"Dynamics of Magnetic Vortices in Ferromagnetic Nanoelements: Micromagnetic Simulations","authors":"T. G. M. Jales;P. V. H. Faustino;Ana L. Dantas;Artur S. Carriço","doi":"10.1109/LMAG.2026.3685976","DOIUrl":"https://doi.org/10.1109/LMAG.2026.3685976","url":null,"abstract":"We present analytical expressions for calculating the dynamic susceptibility of nanostructured magnetic systems and apply them to micromagnetic simulations of vortex dynamics in rectangular Fe and Permalloy (Ni<inline-formula><tex-math>$_{80}$</tex-math></inline-formula>Fe<inline-formula><tex-math>$_{20}$</tex-math></inline-formula>, Py) nanoelements. After magnetic saturation and relaxation to remanence, stable vortex states are obtained, and their excitations are identified through the <inline-formula><tex-math>$chi _{xx}$</tex-math></inline-formula> component of the susceptibility tensor under a weak transverse oscillating field. For <inline-formula><tex-math>$60,text{nm} times 80,text{nm} times text{30},text{nm}$</tex-math></inline-formula> nanoelements, Fe exhibits excitations at 0.65, 1.55, and 2.56 GHz, while Py shows excitations at 0.29, 0.75, and 0.97 GHz. The lowest-frequency mode is localized in the vortex core, whereas the higher frequency modes correspond to edge excitations and excitations localized at internal regions of the nanoelement. The reduced frequencies of Py excitations are attributed to its lower saturation magnetization and exchange stiffness.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"17 ","pages":"6100205-6100205"},"PeriodicalIF":1.1,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148171773","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}

{"title":"Interslice Adhesion-Free Preparation of Tb-Diffused Nd–Fe–B Permanent Magnets via a Controlled Oxidation Strategy","authors":"Jian Yang;Song Fu;Weiwei Que","doi":"10.1109/LMAG.2026.3703123","DOIUrl":"https://doi.org/10.1109/LMAG.2026.3703123","url":null,"abstract":"The coercivity for 5 mm thick magnets was enhanced by 0.85T after Tb grain boundary diffusion process (GBDP). However, the magnet slices easily stuck together due to the formation of a stalactite-like structure consisting of coarse (Nd, Tb)₂Fe₁₄B grains and (Nd, Tb)-rich phases. By preoxidizing the magnet surface before or after Tb coating, (Nd, Tb)-oxides formed in the outer layer during GBDP, which effectively suppressed the interslice sticking. Excessive nonmagnetic (Nd, Tb)-oxides degrade remanence and coercivity by disrupting grain boundary continuity and hindering Tb diffusion. Preoxidation performed after Tb coating restricted oxygen penetration into the magnet interior during GBDP. Meanwhile, appropriate oxygen dissolution promoted the formation of a continuous Nd-rich grain boundary phase, further slightly improving coercivity. Thus, preoxidation following Tb coating represents a promising strategy to preserve the beneficial effects of grain boundary diffusion while eliminating interslice adhesion.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"17 ","pages":"7500404-7500404"},"PeriodicalIF":1.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148482217","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}

{"title":"Pulse Shaping to Mitigate the Impact of Device Imperfections in Field-Free Switching Using Combined Spin-Orbit and Spin-Transfer Torques","authors":"Kuldeep Ray;Jérémie Vigier;Sylvain Martin;Chloé Bouard;Nicolas Lefoulon;Marc Drouard;Gilles Gaudin","doi":"10.1109/LMAG.2026.3685166","DOIUrl":"https://doi.org/10.1109/LMAG.2026.3685166","url":null,"abstract":"Combining spin-orbit torque (SOT) and spin-transfer torque (STT) provides a practical approach for field-free switching in spin-orbit torque magnetic random-access memory (SOT-MRAM), a prerequisite for industrial deployment, but can compromise reliability through phenomena such as backhopping, especially in top-pinned stacks commonly used for SOT-MRAM. We investigate the write error rate (WER) of combined SOT + STT switching in top-pinned devices that are not optimized for STT switching. Experiments reveal clear indications of STT-induced backhopping and a pronounced field-free SOT switching asymmetry between antiparallel-to-parallel and parallel-to-antiparallel transitions. Our macrospin model, using two coupled Landau–Lifshitz–Gilbert equations for the free and the reference layers, qualitatively reproduces this asymmetry and reveals an intermediate loss-of-determinism regime in addition to the well-known backhopping region. Based on these simulations, we develop mitigation strategies and experimentally demonstrate that STT pulse shaping reduces WER and improves switching robustness in the presence of device imperfections.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"17 ","pages":"4500305-4500305"},"PeriodicalIF":1.1,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148171577","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}

{"title":"Toward Realization of Bulk L10-FeNi","authors":"Dimitrios Niarchos;Margarit Gjoka;Vassilis Psycharis;Alexandra Ioannidou;Eamonn Devlin;Athanasios Sigalos;Dimitrios I. Anyfantis","doi":"10.1109/LMAG.2026.3663904","DOIUrl":"https://doi.org/10.1109/LMAG.2026.3663904","url":null,"abstract":"In this letter, we demonstrate for the first time the preparation of bulk L1₀-FeNi embedded in an fcc FeNi by alloying Fe and Ni during casting with 5%–10% indium metal and annealing at 350 °C for a week. From X-ray diffraction, magnetization, and Mössbauer data, we have strong indications that the L1₀-FeNi phase is formed and coexists with the cubic A1-FeNi at a ratio of 30/70 for the sample with 5% In and 20/80% for the sample with 10% In, as derived from X-ray diffraction. This finding is supported by the Mössbauer data, where the ratio of L1₀-FeNi to A1-FeNi is 48/52 and 24/76, respectively. The morphology of the alloys is sponge-like and very brittle, and the final In stoichiometry is much less than the nominal one.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"17 ","pages":"1-5"},"PeriodicalIF":1.1,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11393511","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147557790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Computationally Efficient Fixed-Mesh Finite Element Framework for Coaxial Magnetic Gears Using Subelement Quadrature Boundary Smoothing and Calibrated Analytical Stability Mapping","authors":"Abdelileh Mabrouk","doi":"10.1109/LMAG.2026.3733328","DOIUrl":"https://doi.org/10.1109/LMAG.2026.3733328","url":null,"abstract":"This letter presents a computationally efficient two-dimensional finite element (FE) framework for coaxial magnetic gears (MGs) that couples a fixed-mesh magnetostatic solver with a calibrated analytical stability model to evaluate combined thermal and vibration faults. The fixed-mesh approach employs a subelement quadrature boundary smoothing technique to resolve material boundaries during eccentric rotor displacements without remeshing, enabling rapid parameteric sweeps. Key FE results—stall torque, air-gap field decay length <inline-formula><tex-math>$L_{c}$</tex-math></inline-formula>, and worst-case demagnetizing field <inline-formula><tex-math>$H_{mathrm{op,max}}$</tex-math></inline-formula>—calibrate a reduced-order analytical model that generates stability margin maps, demagnetization safety-factor contours, and dynamic pole-slip predictions. For an neodymium magnet (NdFeB)-based MG with a 4:11 pole-pair combination and a 7 mm inner air gap, the FE solution (torque computation validated via an independent inner/outer contour gear-ratio self-consistency check, agreeing with the theoretical ratio <inline-formula><tex-math>$p_{2}/p_{1}$</tex-math></inline-formula> to within 4.0%) gives a stall torque of 1.169 N<inline-formula><tex-math>$cdot$</tex-math></inline-formula>m/m and <inline-formula><tex-math>$H_{mathrm{op,max}}=342.7$</tex-math></inline-formula> kA/m, with a fitted air-gap decay length <inline-formula><tex-math>$L_{c}=9.44$</tex-math></inline-formula> mm. The calibrated reduced-order model reproduces independent FE evaluations at ten combined temperature-eccentricity operating points to within 10.9% mean error (range 1.6%–21.6%, growing with eccentricity). At 80% of stall torque, the low static stability margin drives pole-slip in 9.8 s, whereas at 60% load the system survives 51.4 s before thermal degradation causes loss of synchronism. The methodology provides a rapid design-screening tool linking FE data with scaled operational stability assessments.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"17 ","pages":"2100305-2100305"},"PeriodicalIF":1.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149188857","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}

{"title":"Magnetic Tunnel Junction-Based Stochastic Logic Gates","authors":"Hao Chen;Brad Parks;Haolin Pan;Yan Wen;Qiang Zhang;Xixiang Zhang;Sara A. Majetich","doi":"10.1109/LMAG.2026.3685974","DOIUrl":"https://doi.org/10.1109/LMAG.2026.3685974","url":null,"abstract":"Magnetic tunnel junctions with voltage-controllable telegraphing between the parallel and antiparallel states were combined with hybrid circuits to create probabilistic bit modules. The time-dependent behavior was measured both when these devices were free running and when they were coupled together to form stochastic logic gates. Two modules were used to create a nearly deterministic NOT gate. A stochastic AND gate was demonstrated using a combination of three modules, and a statistical preference for microstates consistent with the AND gate truth table was observed. A metric is developed for quantifying the performance through pairwise comparison of microstate probabilities.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"17 ","pages":"4500405-4500405"},"PeriodicalIF":1.1,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148003498","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}

{"title":"Optomechanical Ising Machine","authors":"Elizaveta Soboleva;Semyon Rudyi;Andrei Ivanov","doi":"10.1109/LMAG.2026.3706952","DOIUrl":"https://doi.org/10.1109/LMAG.2026.3706952","url":null,"abstract":"The Ising machine is a promising solver for quadratic unconstrained binary optimization problems. Its core principle is finding the global minimum of the Ising Hamiltonian in a physical system. We developed an alternative optomechanical platform for the Ising machine solver based on a hybrid optical-electrodynamical trap that enables controllable spatial bifurcation to create artificial spin states. In this work, we present a time-multiplexing architecture to solve combinatorial optimization problems on the developed optomechanical platform. Time division multiplexing allows for the scale spin network with Ising spin connections for different graph topologies. We also discuss advantages and challenges of the time-multiplexing concept for a levitodynamical platform with continuous dynamics.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"17 ","pages":"2100205-2100205"},"PeriodicalIF":1.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148627549","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}

{"title":"Power Analysis Attack Resilient 9T and 10T NVSRAM for Emerging Memory","authors":"Sandeep Tripathi;Pritesh Kumar Yadav;Sudhanshu Choudhary;Prasanna Kumar Misra","doi":"10.1109/LMAG.2026.3693614","DOIUrl":"https://doi.org/10.1109/LMAG.2026.3693614","url":null,"abstract":"A power analysis (PA) attack resilient 9T and 10T nonvolatile static random-access memory (NVSRAM) bit cell is presented in this letter. The write mode, store mode, and restore mode operations of the NVSRAM are vulnerable due to its single-stage operation. In single-stage write and restore operations, if the stored data at the charging nodes are the same as the processed data, then no bit-flip is required at the charging nodes. Otherwise, a bit-flip is required. The power consumption difference between bit-flip and no bit-flip forms a strong correlation. Similarly, in the store operation, different critical currents are needed for storing logic “0” and logic “1,” which forms a correlation. Attackers exploit these correlations to obtain the stored information. The developed NVSRAM bit cell with two-stage write, store, and restore operations offers PA attack resilience by reducing the power consumption correlation between processed data and stored data. The two-stage operation consists of equalization and the flip process. The two-stage operation offers a weak energy correlation (75x/120x less compared to a single-stage operation) between stored data and processed data, resulting in PA attack resilience. In addition, two different types of store operations for the cell have been designed: one using word lines (WLs) and bit lines (BLs), and the other one without using the same.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"17 ","pages":"1-5"},"PeriodicalIF":1.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148747110","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}

{"title":"Localization of the Skyrmion Phase in a Perforated Magnetoelectric Film With Dzyaloshinskii–Moriya Interaction","authors":"Ildus F. Sharafullin;Alina R. Yuldasheva;Danil I. Abdrakhmanov;Angela I. Samigullina","doi":"10.1109/LMAG.2026.3715097","DOIUrl":"https://doi.org/10.1109/LMAG.2026.3715097","url":null,"abstract":"We study the effect of a circular hole-shaped structural defect on the size and density of skyrmions in a perforated magnetoelectric film using the steepest descent method and Monte Carlo simulations. Achieving controllable skyrmion density opens up possibilities for the design of functional skyrmion-based devices. We show that the presence of a hole-shaped defect in the ferroelectric layer leads to a remarkable localization effect in the second (magnetic) monolayer. This effect has clear potential for practical applications, as it solves the important problem of localizing skyrmions at specific predetermined positions. The defect enables stable localization of skyrmions in the magnetic layer directly beneath the hole. To verify the thermal stability of the skyrmions and the skyrmion lattice phase, we performed Monte Carlo simulations and calculated the order parameter and susceptibility. The results obtained can be useful for evaluating the “potential capabilities” of specific defect sizes and interaction parameters in magnetoelectric materials for achieving high transition temperatures in the presence of a strong in-plane Dzyaloshinskii–Moriya interaction.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"17 ","pages":"5100105-5100105"},"PeriodicalIF":1.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148781287","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}

{"title":"A Comprehensive Modeling and Benchmarking Framework for Two-Terminal In-Plane Magnetic Anisotropy SOT-MRAM","authors":"Md Nahid Haque Shazon;Daniel C. Ralph;Azad Naeemi","doi":"10.1109/LMAG.2026.3685980","DOIUrl":"https://doi.org/10.1109/LMAG.2026.3685980","url":null,"abstract":"In this study, a modeling and benchmarking framework is presented to assess compact two-terminal (2T) in-plane magnetic anisotropy spin-orbit torque magnetic random-access memory (IMA SOT-MRAM) cells. Although a previously proposed one-transistor one-magnetic tunnel junction configuration, with its 2T configuration, offers a more compact cell design that improves the cell density compared to a three-terminal (3T) design, it suffers from significant current crowding at the edge of the device and does not provide any notable advantage in terms of write time or energy. Here, we analyze a 2T variant incorporating a fixed layer with a length half of the free layer; this increases the effective path electrons pass through the SOT layer and provides a measurable benefit in terms of write energy and conduction current density. Two materials for the SOT channel—AuPt and β–W—are investigated. With the β–W SOT channel, the IMA 2T SOT-MRAM cell featuring a half-fixed layer achieves a 25% decrease in maximum conduction current density and a 16% decrease in write energy compared to the conventional 3T IMA SOT-MRAM. Also, the maximum conduction current densities for the IMA cases are significantly lower compared to those of the field-assisted perpendicular magnetic anisotropy case. These results indicate that the half-fixed 2T architecture—when paired with CMOS-compatible β–W —offers a practical path to denser, lower energy in-plane SOT-MRAMs.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"17 ","pages":"4500505-4500505"},"PeriodicalIF":1.1,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148003511","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}