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":"Influence of geometrical parameters of magnetic nanoparticles in a linear chain on the conditions for generation, structure, and properties of discrete breathers","authors":"Dmitry A. Kuzmin ,&nbsp;Igor V. Bychkov ,&nbsp;Evgenii G. Ekomasov","doi":"10.1016/j.jmmm.2025.173250","DOIUrl":"10.1016/j.jmmm.2025.173250","url":null,"abstract":"<div><div>The study investigates the magnetization dynamics in one-dimensional chains of elliptical magnetic nanoparticles interacting via dipole–dipole interactions. Numerical simulations of the Landau–Lifshitz (LL) equations demonstrate the possibility of localized nonlinear high–amplitude magnetization oscillations in such nanoparticle chains, which manifest as discrete breathers (or intrinsic localized modes). These solutions consist of a “core,” where the magnetization vectors precess around a hard axis, and “tails,” where they oscillate around the equilibrium state. Analytical estimations of the breather frequency agree well with the numerical simulation results. The influence of the nanoparticles’ geometrical parameters on discrete breathers in a linear chain is determined. Analysis of the frequency expression shows that breathers can exist only when one of the principal axes—specifically, the one oriented perpendicular to the chain direction—is significantly smaller than the other two; that is, when the particles are nearly disk–shaped.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173250"},"PeriodicalIF":2.5,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144220854","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":"Effects of Pr in Tb-Pr-M diffusion source on grain boundary diffusion behavior of sintered Nd-Fe-B magnets","authors":"E Niu,&nbsp;Fei Du,&nbsp;Zhan Wang,&nbsp;Yangzi Fu,&nbsp;Fei Li,&nbsp;Juan Yang,&nbsp;Yuchen Yao,&nbsp;Xiaolei Rao,&nbsp;Boping Hu","doi":"10.1016/j.jmmm.2025.173256","DOIUrl":"10.1016/j.jmmm.2025.173256","url":null,"abstract":"<div><div>To identify the effects of Pr in the grain boundary diffusion (GBD) source on sintered Nd-Fe-B magnet, Tb₇₀M₃₀(M=Co, Al) and Tb₃₅Pr₃₅M₃₀ alloys were prepared as the diffusion sources. These two types GBD samples were made with the same Tb weight gain and heat treatment for 2 h and 8 h, respectively. The distribution of element Tb and the coercivity were jointly investigated. The micro-morphology and distribution of rare earth elements show that the presence of Pr significantly boosts the diffusion efficiency of Tb. With the assistant of Pr, after a short time heat treatment, the excessive aggregation of Tb near the coated surface is prevented, allowing Tb to diffuse more deeply into the magnet. This leads to a greater coercivity enhancement of the entire magnet and higher local coercivity at different depth from the coating surface. However, when the diffusion time is extended, Pr induces much thinner shell and lower Tb concentration in the grain shells near the surface, and promotes a more homogeneous distribution of Tb in the magnet diffused with Tb₃₅Pr₃₅M₃₀. Moreover, a more uniform distribution of local coercivity, characterized by a reduction of local coercivity enhancement at the surface and a substantial increase of local coercivity enhancement inside of the magnet, was detected in the magnet diffused Tb₃₅Pr₃₅M₃₀. This contradiction results in the smaller increment of coercivity of the entire magnet than that of the magnet diffused with Tb₇₀M₃₀. The study reveals the importance of balancing these two main effects caused by the addition of Pr in the diffusion source under various diffusion conditions, which is helpful for the industry to develop the high-efficiency grain boundary diffusion technology.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173256"},"PeriodicalIF":2.5,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144322170","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":"Four compensation points in TbxCo100-x amorphous films","authors":"Akane Agui ,&nbsp;Akino Harako ,&nbsp;Naruki Tsuji ,&nbsp;Xiaoxi Liu ,&nbsp;Kazushi Hoshi ,&nbsp;Kosuke Suzuki ,&nbsp;Manabu Takahashi ,&nbsp;Hiroshi Sakurai","doi":"10.1016/j.jmmm.2025.173248","DOIUrl":"10.1016/j.jmmm.2025.173248","url":null,"abstract":"<div><div>We investigated the temperature and composition dependencies of the magnetic moment in Tb<em>_x</em>Co_100-<em>_x</em> using magnetic Compton scattering and SQUID measurements. We discovered new magnetic compensation points where spin magnetic compensation occurs with zero net spin magnetization, though the total magnetization remains nonzero. A similar compensation was observed for the orbital magnetic moment. This is the first report to document the existence of at least four compensation points—magnetic, angular momentum, spin, and orbital—in ferrimagnetic films and to describe the relationship between them. These compensation points are expected to be key parameters in spintronics technologies, particularly for the design of perpendicular magnetic anisotropy, spin polarization, topological properties, and high-speed magnetic response techniques.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173248"},"PeriodicalIF":2.5,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144240078","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":"Searching for magnetically hard monoborides (and finding a few): A first-principles investigation","authors":"Justyn Snarski-Adamski,&nbsp;Mirosław Werwiński","doi":"10.1016/j.jmmm.2025.173204","DOIUrl":"10.1016/j.jmmm.2025.173204","url":null,"abstract":"<div><div>New hard magnetic materials with zero or low rare earth content are in demand due to the high and volatile prices of the rare earth metals. Among the candidates for such materials, we consider MnB, FeB and their alloys, since previous experiments suggest that FeB has a relatively high magnetic hardness of about 0.83 at room temperature. Using first-principles calculations, we examine the full range of alloys from CrB, through MnB, FeB, to CoB. Furthermore, we consider alloys of MnB and FeB with substitutions of 3<span><math><mi>d</mi></math></span>, 4<span><math><mi>d</mi></math></span> and 5<span><math><mi>d</mi></math></span> transition metals. For the above compositions, we determine magnetic moment, magnetocrystalline anisotropy energy and magnetic hardness. For the alloys with transition metals, we calculated also formation energies and Curie temperatures. The most accurate MAE calculations performed for (Fe-Co)B alloys using supercells indicate both semi-hard and hard magnetic compositions. The weak point of these alloys, however, is the relatively low values of Curie temperatures and magnetic moments. Furthermore, we classify considered MnB alloys substituted with transition metals as magnetically soft or semi-hard and FeB alloys with Sc, Ti, V, Zr, Nb, Mo, Hf, Ta, or W as magnetically hard (with magnetic hardness exceeding unity). However, the most promising elements for FeB alloying are Mn and Cr, because by increasing the magnetic hardness of the alloy (below unity), they increase or only a little decrease its Curie temperature, respectively.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173204"},"PeriodicalIF":2.5,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144263271","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}