Journal of Magnetism and Magnetic Materials最新文献

{"title":"Proposal of hybrid-type simulation techniques for spherical magnetic nanoparticles with uniaxial anisotropy: A combination of Brownian dynamics and Monte Carlo methods achieving fast and scalable simulations","authors":"Kazuya Okada ,&nbsp;Akira Satoh","doi":"10.1016/j.jmmm.2025.173259","DOIUrl":"10.1016/j.jmmm.2025.173259","url":null,"abstract":"<div><div>We developed a hybrid-type simulation method that combines the Brownian dynamics (BD) and Monte Carlo (MC) methods for spherical magnetic particles with uniaxial magnetic anisotropy. In this hybrid-type simulation method, the viscous translational and rotational motions of a magnetic particle are simulated using the BD method, where the direction of the magnetic moment of the particle is determined using the MC method instead of the stochastic Landau–Lifshitz–Gilbert (LLG) method. We addressed a single-particle system to investigate the orientational properties of both the particle and magnetic moment. In order to verify the validity of the hybrid-type method, the present results were compared with those obtained by solving a stochastic LLG equation. With respect to the magnetisation curve, the hybrid-type simulation method gives rise to a theoretical solution (Langevin function), just as in the stochastic LLG simulation method. The orientational characteristics of the particle and the magnetic moment, as a function of the value of the magnetic anisotropy and as a function of the magnetic field strength, agreed well between the two simulation methods. Even if the anisotropic factor is more dominant than the thermal motion, the magnetic particle behaves as a superparamagnetic particle in a sufficiently strong magnetic field. The developed hybrid-type simulation method provides significantly higher performance with respect to CPU time in comparison with the stochastic LLG method, which is the most appealing aspect of the present simulation method. This CPU time may be a definitive factor in determining the feasibility of a particle-based simulation method for a multi-particle system. We conclude that the present hybrid-type simulation method is remarkably effective and practical for simulations of a multi-particle system where the motion of both the particle and the magnetic moment are governing factors, for instance, in studies on magnetic hyperthermia.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173259"},"PeriodicalIF":2.5,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144203081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancing magnetic performance through microstructure optimization in hydrogenation-disproportionation-desorption-recombination Nd-Fe-B powders","authors":"Yuan-Fei Yang ,&nbsp;Xu-Hua Wang ,&nbsp;Ning-Tao Quan ,&nbsp;Yang Luo ,&nbsp;Zi-Long Wang ,&nbsp;Dun-Bo Yu ,&nbsp;Zhong-Kai Wang ,&nbsp;Tian-Hao Li ,&nbsp;Jian-Hui Dong ,&nbsp;Yang Lu ,&nbsp;Wen-Hui Ma","doi":"10.1016/j.jmmm.2025.173254","DOIUrl":"10.1016/j.jmmm.2025.173254","url":null,"abstract":"<div><div>The intricate correlation between microstructural variances and magnetic properties of hydrogenation-disproportionation-desorption-recombination (HDDR) Nd₂Fe₁₄B magnets was investigated. Magnetic properties of HDDR powders vary with the change of particle size, chemical composition, oxygen content, and microstructure, all of which are characterized. The focused ion beam transmission electron microscope (FIB-TEM) was utilized to observe microstructure in the sample, semi-quantitative revealing the differences between the internal and external regions of the powders. Microstructure optimization enhances the remanence and maximum energy product of Nd-Fe-B powders. The impact of microstructure on magnetic properties is also elucidated by a finite element software system. The microstructure and magnetic properties of HDDR powders were optimized by adjusting the macroscopic morphology of the particles.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173254"},"PeriodicalIF":2.5,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144203082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Superparamagnetic nanoparticles vs. ferromagnetic nanowires: a comparative simulation study for high-frequency inductor applications","authors":"Chih-Chen Peng ,&nbsp;Cheng-Jun Wu ,&nbsp;Sheng-Chih Lai ,&nbsp;Chen-Yu Hu ,&nbsp;Mingyuan Song ,&nbsp;Xinyu Bao ,&nbsp;Yu-Ming Lin ,&nbsp;Chi-Feng Pai","doi":"10.1016/j.jmmm.2025.173221","DOIUrl":"10.1016/j.jmmm.2025.173221","url":null,"abstract":"<div><div>Magnetic core materials play a crucial role in advancing the performance of high-frequency on-chip inductors. This study investigates two promising candidates, superparamagnetic nanoparticles (SPM NPs) and ferromagnetic thin-film nanowires (FM NWs), through comprehensive simulations to evaluate their potential for high-frequency applications. For the SPM NP system, we demonstrate that increasing saturation magnetization (<em>M</em>_s) and damping constant significantly improves performance, while inter-particle interactions influence material characteristics depending on packing geometry. For the FM NW system, a bi-anisotropy model based on shape anisotropy shows that <em>M</em>_s is the primary factor limiting frequency performance. Under the consideration of dipolar field effect, the system achieves an effective permeability (<em>μ</em>_eff) of 1.62 and a ferromagnetic resonance frequency (<em>f</em>_r) of 17.1 GHz with an <em>M</em>_s of 1000 emu/cc. In conclusion, analytical formulas are provided to account for volume fraction, enabling performance prediction and optimization for both systems. While SPM NPs can achieve higher frequency limit, they are limited in <em>μ</em>_eff. In contrast, FM NWs offer a better balance between <em>μ</em>_eff and <em>f</em>_r. This simulation-based study offers valuable insights into the trade-offs and design considerations for magnetic core materials in next-generation high-frequency inductors.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173221"},"PeriodicalIF":2.5,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144203084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnetic properties and magnetocaloric effect of Gd1−xDyxVO4 (0 ≤ x ≤ 0.8) at low temperature","authors":"Guoming Lv ,&nbsp;Xiukun Hu ,&nbsp;Jiage Jia ,&nbsp;Jianghuan Shi ,&nbsp;Yi Zhao ,&nbsp;Hongliang Ge ,&nbsp;Hangfu Yang ,&nbsp;Qiong Wu","doi":"10.1016/j.jmmm.2025.173252","DOIUrl":"10.1016/j.jmmm.2025.173252","url":null,"abstract":"<div><div>Rare-earth vanadates have gained considerable attention owing to their unique structure and physical properties, making them suitable for applications in optical and magnetic devices. Herein, a novel Gd and Dy doped vanadate compound Gd_1−xDy_xVO₄ (0 ≤ x ≤ 0.8) (GDVO) was synthesized via solid-state sintering, and its magnetocaloric effect (MCE) was investigated. Results of X-ray diffraction analysis show that all the samples formed a single phase with the I41/amd space group of zircon-type compounds. The zero-field-cooling and field-cooling curves indicate that the phase transition temperature of the sample may be below 2 K and the antiferromagnetic coupling weakens with increasing Dy content. Under an external magnetic field change of 5 T (1 T), the maximum magnetic entropy change and the relative cooling power (RCP) of the GDVO samples can be tuned in the range of 26.59–36.67 J/(kg·K) (3.69–7.79 J/(kg·K)) and 231.85–398.82 J/kg (11.64–38.98 J/kg), respectively, for 0 ≤ x ≤ 0.8. Based on the mean-field theory, the power-law fit of the curve suggests that the there is a short-range ordered interaction in GDVO. The enhancement of the magnetic entropy change and RCP under low magnetic fields by element doping provides effective support for optimizing the MCE of the material. Moreover, GDVO exhibits an excellent MCE, making it promising for cryogenic refrigeration technology.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173252"},"PeriodicalIF":2.5,"publicationDate":"2025-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144194577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Superparamagnetism in systems with magnetostatic interaction","authors":"V. Belokon ,&nbsp;O. Dyachenko","doi":"10.1016/j.jmmm.2025.173198","DOIUrl":"10.1016/j.jmmm.2025.173198","url":null,"abstract":"<div><div>Superparamagnetism in systems with magnetostatic interaction is evaluated. Equations describing the dynamics of particle flipping under the influence of a magnetic field are presented, formulas for the relaxation time and magnetic susceptibility of particles are derived, and the frequency factor is estimated. Experimental data demonstrating a decrease in the susceptibility peak with increasing field are also discussed.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173198"},"PeriodicalIF":2.5,"publicationDate":"2025-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144194578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spin ordering in a lattice of separated FeO4 tetrahedra: case of Ba2YFeO5","authors":"V. Caignaert ,&nbsp;Y. Bréard ,&nbsp;A.K.K. Kundu ,&nbsp;B. Raveau ,&nbsp;B. Gonano ,&nbsp;V. Hardy","doi":"10.1016/j.jmmm.2025.173249","DOIUrl":"10.1016/j.jmmm.2025.173249","url":null,"abstract":"<div><div>The magnetic structure of Ba₂YFeO₅ below <em>T_N</em> (∼ 5.5 K) is established on the basis of powder neutron diffraction. The only magnetic species in this compound is Fe³⁺, which is distributed onto a 3D framework of FeO₄ tetrahedra separated by YO₆ octahedra. The leading magnetic interaction is the super-super-exchange (SSE) between Fe³⁺ cations via two O^2– anions. The magnetic structure can be described by an alternation of two types of corrugated layers carrying spins being “up” or “down” along a certain direction. This ordering is discussed in connection with the topology and relative strengths of the main SSE couplings. It is found that additional mechanisms, such as crystal-field effects and dipolar interactions, likely come into play to achieve the observed spin order.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173249"},"PeriodicalIF":2.5,"publicationDate":"2025-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144194579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microwave-assisted rapid synthesis of NiCo2O4 with high-performance electromagnetic wave absorption","authors":"Yujin Duan ,&nbsp;Zijun Xie ,&nbsp;Miaomiao Du ,&nbsp;Xianting Feng ,&nbsp;Qing Chang","doi":"10.1016/j.jmmm.2025.173207","DOIUrl":"10.1016/j.jmmm.2025.173207","url":null,"abstract":"<div><div>Despite the prosperous development in synthesis methods and electromagnetic wave absorption performance of NiCo₂O₄, the green and rapid synthesis process of high-performance NiCo₂O₄ with large-scale production is still lack so far. Herein, a microwave-assisted rapid synthesis method was proposed for the first time to harvest NiCo₂O₄, which shortened the preparation time of precursor to 90 s and significantly improved the production efficiency. The type of metal salts and cosolvents were optimized to explore the dominant loss mechanism and improve the electromagnetic wave absorption performance of NiCo₂O₄. The best performance appears in the sample resulting from acetates and ethanol (A-Et), with an effective absorption bandwidth of 6.24 GHz (1.9 mm), and minimum reflection loss of −40.40 dB (5.24 GHz, 3.0 mm). The existence of oxygen vacancy and lattice defect dominate the electromagnetic wave loss mechanism of A-Et. This study provides a new insight for the rapid green synthesis of high-performance NiCo₂O₄.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173207"},"PeriodicalIF":2.5,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144212900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improved properties of Fe-Ni-Mo soft magnetic composites via particle surface modification","authors":"Qi Li ,&nbsp;Zhangqiao Zhou ,&nbsp;Yan Nie ,&nbsp;Lu Yang ,&nbsp;Yu Wang ,&nbsp;Jinsong Chen ,&nbsp;Xian Wang","doi":"10.1016/j.jmmm.2025.173220","DOIUrl":"10.1016/j.jmmm.2025.173220","url":null,"abstract":"<div><div>The preparation of soft magnetic composites requires effective surface modification of alloy powder to enhance insulating properties and achieve dense, uniform coating layers. Firstly, the gas-atomized Fe-Ni-Mo powder was surface modified using the atomic layer deposition method, forming a uniform and dense Al₂O₃ insulating layer. The secondary surface modification of organic polymers further improves the properties of soft magnetic composites. This study systematically evaluates the effects of the primary and secondary surface modification on the properties of powder particles and soft magnetic composites. The primary modification generates an extremely thin insulating layer of approximately 2.5 nm, which increases the particle resistivity by 9 orders of magnitude. The permeability frequency stability of the soft magnetic composites increased from 11.3 % to 96.5 %, resulting in significant core loss reduction. The secondary modification effectively enhances the formability of soft magnetic composites. Optimal permeability of 242.7 at 1 kHz is achieved, maintaining 95.2 % frequency stability up to 1 MHz, while core loss remains below 570 mW cm⁻³ under 100 kHz/100 mT conditions. The surface treatment method in this work can provide a reference for the surface insulation modification of soft magnetic composites.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173220"},"PeriodicalIF":2.5,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144203083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Viable scaling mechanism ensuing anomalous Hall effect in Si/Ni multilayers from 2 K-300 K","authors":"Dushyant Singh ,&nbsp;Shivesh Yadav ,&nbsp;Krista R. Khiangte","doi":"10.1016/j.jmmm.2025.173222","DOIUrl":"10.1016/j.jmmm.2025.173222","url":null,"abstract":"<div><div>A systematic study of the scaling mechanisms driving the anomalous Hall effect (AHE) in Si/Ni multilayers was conducted from 2 K to 300 K on <span><math><msub><mrow><mo>[</mo><mi>S</mi><mi>i</mi><mrow><mo>(</mo><mn>40</mn><mi>Å</mi><mo>)</mo></mrow><mo>/</mo><mi>N</mi><mi>i</mi><mrow><mo>(</mo><msub><mi>t</mi><mrow><mi>N</mi><mi>i</mi></mrow></msub><mi>Å</mi><mo>)</mo></mrow><mo>]</mo></mrow><mn>20</mn></msub></math></span>​ multilayers. Structural analysis revealed polycrystalline Ni layers and amorphous Si layers. As <span><math><msub><mi>t</mi><mrow><mi>N</mi><mi>i</mi></mrow></msub></math></span>​ decreased, Ni nanocrystallite size reduced, while the surface-to-volume ratio and Si/Ni interface roughness increased. Multilayers with <span><math><mrow><msub><mi>t</mi><mrow><mi>N</mi><mi>i</mi></mrow></msub><mo>≥</mo><mn>40</mn><mi>Å</mi></mrow></math></span> exhibited ferromagnetic behavior, while those with <span><math><mrow><msub><mi>t</mi><mrow><mi>N</mi><mi>i</mi></mrow></msub><mo>&lt;</mo><mn>40</mn><mi>Å</mi></mrow></math></span> were superparamagnetic. Decreasing <span><math><msub><mi>t</mi><mrow><mi>N</mi><mi>i</mi></mrow></msub></math></span> also increased longitudinal resistivity due to enhanced interface roughness, higher surface-to-volume ratio, and increased tunneling between Ni nanocrystallites. AHE studies showed that Hall resistance peaked with decreasing <span><math><msub><mi>t</mi><mrow><mi>N</mi><mi>i</mi></mrow></msub></math></span>​ but declined for <span><math><mrow><msub><mi>t</mi><mrow><mi>N</mi><mi>i</mi></mrow></msub><mo>&lt;</mo><mn>40</mn><mi>Å</mi></mrow></math></span>, due to superparamagnetism. Skew scattering dominated Hall resistance enhancement at all temperatures, but as the temperature increased from 2 K to 300 K, a transition from skew scattering to the side-jump mechanism was observed.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173222"},"PeriodicalIF":2.5,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144178806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A strategy for improving inherent brittleness without significantly sacrificing the magnetocaloric effect in a Ni-Mn-Sn Heusler alloy","authors":"Qiang Zhai ,&nbsp;Fan Bu ,&nbsp;Yuhao Cheng ,&nbsp;Jiaqi Zhang ,&nbsp;Yixuan He","doi":"10.1016/j.jmmm.2025.173246","DOIUrl":"10.1016/j.jmmm.2025.173246","url":null,"abstract":"<div><div>The eutectic design, a prevalent strategy for enhancing mechanical properties, aims to address the poor workability caused by the high brittleness of L2₁ intermetallic phase in Ni-Mn-Sn Heusler alloy as a promising material for solid-state refrigeration. In this study, a eutectic composition of Ni₄₈Co₁₀Mn₃₂Sn₁₀ with a fully L2₁/γ lamellar structure significantly improves mechanical properties, reaching 1950 MPa fracture strength and 20.5 % ductility. However, the desired magnetocaloric effect (MCE) is completely inhibited due to a strong Kurdyumov and Sachs orientation relationship (K-S OR) between eutectic phases. To overcome these challenges, a solution to precipitate primary L2₁ phase is proposed. This approach breaks the K-S OR by promoting epitaxial growth of the L2₁ eutectic phase on the primary L2₁ phase. Consequently, the hypoeutectic Ni₄₈Co₈Mn₃₄Sn₁₀ composition achieves an excellent balance between MCE and mechanical properties, with a maximum magnetic entropy change of 10.13 J kg⁻¹ K⁻¹ under 5 T magnetic field, 1894 MPa fracture strength, and 18.4 % ductility. Our strategy overcomes inherent brittleness without significantly sacrificing the magnetocaloric effect within Ni-Mn-Sn alloys. This study is pivotal for optimizing the structural design and properties of Ni-Mn based Heusler alloys.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173246"},"PeriodicalIF":2.5,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144168352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}