Journal of Magnetism and Magnetic Materials最新文献_第10页

Effects of laser cutting and post-processing on the microstructure and properties of thin sintered Nd-Fe-B magnets 激光切割和后处理对烧结Nd-Fe-B薄磁体组织和性能的影响

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2026-03-01 Epub Date: 2026-01-14 DOI: 10.1016/j.jmmm.2026.173838

Lichun Zhan , Wenyu Pan , Ruihua Du , Weiqiang Liu , Zan Long , Shengli Jia , Qifeng Wei , Xiongfei Wu , Ming Yue

Laser cutting, recognized for its narrow kerf, high efficiency, and adaptability to complex geometries, is increasingly employed in the machining of thin sintered Nd–Fe–B magnets. This work systematically evaluates the influence of laser cutting versus conventional multi-wire cutting combined with grinding on the microstructure, mechanical strength, and magnetic properties of magnets under black, chamfered, and pickled conditions. Laser cutting induces stepped demagnetization curves, lowers intrinsic coercivity and mechanical properties compared to conventional multi-wire cutting combined with grinding method. Results indicate that chamfering improves the three-point bending force of laser-cut samples by approximately 31.4% on average. After pickling, the specific magnetic moment of laser-cut samples is only 0.13% lower, and the irreversible flux loss is merely 0.08% higher than that of ground specimens. Microstructural analysis reveals that laser-cut surfaces contain a resolidified layer, micropores, and networked microcracks, which contribute to the degradation in mechanical and magnetic properties. Magnetic domain observations further demonstrate that laser-cut black samples exhibit blurred domain boundaries and maze domains, whereas chamfered specimens show a marked reduction in maze domains and improved domain alignment. Under identical reverse magnetic fields, domain reversal occurs more readily in black samples than in chamfered ones. In summary, through appropriate parameter selection and post-processing, such as chamfering and pickling, the mechanical and magnetic performance of laser-cut thin Nd-Fe-B magnets can closely match that of ground magnets, offering valuable guidance for process optimization in thin magnet manufacturing.

激光切割以其窄切口、高效率和对复杂几何形状的适应性而被越来越多地应用于烧结钕铁硼薄磁体的加工。本研究系统地评估了在黑色、倒角和酸洗条件下，激光切割与传统多线切割结合磨削对磁体微观结构、机械强度和磁性能的影响。激光切割产生阶梯退磁曲线，与传统的多线切割结合磨削方法相比，具有较低的内在矫顽力和力学性能。结果表明，倒角可使激光切割样品的三点弯曲力平均提高约31.4%。经酸洗处理后，激光切割样品的比磁矩仅比地面样品低0.13%，不可逆磁通量损失仅比地面样品高0.08%。显微结构分析表明，激光切割表面含有再凝固层、微孔和网状微裂纹，这些都导致了机械性能和磁性能的下降。磁畴观察进一步表明，激光切割的黑色样品显示出模糊的畴边界和迷宫畴，而倒角样品显示出迷宫畴的显著减少和改进的畴对齐。在相同的反向磁场下，黑色样品比倒角样品更容易发生畴反转。综上所述，通过适当的参数选择和倒角、酸洗等后处理，激光切割的Nd-Fe-B薄磁体的机械性能和磁性能可以与地面磁体的机械性能和磁性能接近，为薄磁体制造的工艺优化提供了有价值的指导。

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引用次数: 0

Probing the local atomic structure and magnetism in Iron and manganese co-doped indium oxide Nanocubes using XAS and DFT 利用XAS和DFT探测铁锰共掺杂氧化铟纳米立方的局部原子结构和磁性

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2026-03-01 Epub Date: 2026-01-06 DOI: 10.1016/j.jmmm.2026.173814

Manikandan Dhamodaran , Rahul Kumar Yadav , N. Raja , Ramesh Karuppannan , Rajeev Gupta

We examine the impact of iron and manganese co-doping on the local atomic environment in hydrothermally synthesized In₂O₃ using synchrotron X-ray absorption spectroscopy analysis, correlating the findings with the observed magnetic properties. The results revealed that manganese is mainly present in the +3-valence state with a dilute contribution from the +4 state. These oxidation states indicate the formation of oxygen vacancies resulting from charge imbalance. The effective co-substitution of iron and manganese atoms in the In₂O₃ was established, accompanied by specific changes in bond lengths. Additionally, the bond length of MnO slightly increased for In_1.94Fe_0.02Mn_0.04O₃, and subsequently, decreased for the higher Mn-doped samples. Density functional theory calculations revealed that the FeO bond length decreases from 2.194 to 2.141 Å upon the introduction of oxygen vacancies, indicating enhanced FeO interactions. Conversely, the MnO bond increased from 2.140 to 2.210 Å, reflecting the weakened local bonding environment and reduced lattice integration of Mn atoms. Magnetic investigations revealed a room-temperature ferromagnetism in In_1.94Fe_0.02Mn_0.04O₃, characterized by an enhanced coercivity and saturation magnetization. Density functional theory calculations show that oxygen vacancy formation stabilizes the high magnetic moments 3.85 μ_B for Fe and 4.23 μ_B for Mn, driven by FeO and MnO hybridization and increased d-electron localization around the transition metal centers. These findings offer new insights into the local micro-environment and magnetic characteristics of iron and manganese-codoped indium oxide.

我们利用同步x射线吸收光谱分析研究了铁和锰共掺杂对水热合成In2O3中局部原子环境的影响，并将这些发现与观察到的磁性能联系起来。结果表明，锰主要以+3价态存在，+4价态的贡献较小。这些氧化态表明由于电荷不平衡而形成的氧空位。在In2O3中建立了铁和锰原子的有效共取代，并伴随着键长的特定变化。此外，在In1.94Fe0.02Mn0.04O3中，MnO的键长略有增加，随后在mn掺杂较高的样品中，MnO的键长减小。密度泛函理论计算表明，引入氧空位后，FeO键长从2.194减小到2.141 Å，表明FeO相互作用增强。相反，MnO键从2.140增加到2.210 Å，反映了局部键合环境的减弱和Mn原子晶格积分的降低。磁学研究表明，In1.94Fe0.02Mn0.04O3具有室温铁磁性，具有增强的矫顽力和饱和磁化。密度泛函理论计算表明，氧空位的形成稳定了Fe （3.85 μB）和Mn （4.23 μB）的高磁矩，这是由FeO和MnO杂化和过渡金属中心周围d电子局域化的增加所驱动的。这些发现为铁锰共掺杂氧化铟的局部微环境和磁性特性提供了新的见解。

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引用次数: 0

Tunable magnetoelectric antennas enabled by multi-physics synergistic regulation 多物理场协同调节的可调谐磁电天线

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2026-03-01 Epub Date: 2026-01-17 DOI: 10.1016/j.jmmm.2026.173831

Sijie Min, Kai Liu, Na Li, Zeshuo Jiao, Yiqun Zhang, Bin Zheng

The demand for highly miniaturized antennas in micro-unmanned platforms has motivated the exploration of magnetoelectric (ME) antennas, which achieve sound-electric-magnetic energy conversion through the strong coupling between piezoelectric and magnetostrictive layers. Although ME antennas offer extreme size reduction by leveraging bulk acoustic wave resonance, their performance remains limited due to incomplete understanding of multi-physics coupling mechanisms under practical environmental disturbances. In this work, a unified multiphysics model is established based on the constitutive equations of piezoelectric and magnetostrictive materials. Analytical expressions for the inverse magnetoelectric coefficient and acoustic resonance frequency are derived as functions of external stress, magnetic field, and temperature. Simulation results show that moderate stress and bias magnetic field enhance ME coupling efficiency, whereas temperature mainly induces linear frequency drift. Under the parameter-scan ranges and evaluation criteria defined in this work, the recommended combined condition for subsequent tuning-scheme validation is 20 MPa stress, 4000 A/m magnetic field, and 20 °C. Based on these findings, three frequency-tuning approaches DC-voltage tuning, capacitive loading, and integration of a phase-change material layer are further proposed, enabling controllable and wide-range frequency adjustment. The results provide quantitative guidelines for ME antenna design under complex environments and demonstrate clear potential for applications in micro-unmanned platforms and other constrained multiphysics scenarios.

微型无人平台对高度小型化天线的需求推动了磁电（ME）天线的探索，该天线通过压电层和磁致伸缩层之间的强耦合实现声-电-磁能转换。尽管ME天线通过利用体声波共振提供了极大的尺寸减小，但由于对实际环境干扰下的多物理场耦合机制的不完全理解，其性能仍然有限。本文基于压电和磁致伸缩材料的本构方程，建立了统一的多物理场模型。推导了逆磁电系数和声共振频率随外加应力、磁场和温度的解析表达式。仿真结果表明，适度的应力和偏置磁场提高了ME耦合效率，而温度主要引起线性频率漂移。在本工作定义的参数扫描范围和评价标准下，后续调谐方案验证的推荐组合条件为20 MPa应力，4000 A/m磁场，20°C。在此基础上，进一步提出了直流电压调谐、电容加载和相变材料层集成三种频率调谐方法，实现了可控和宽范围的频率调节。研究结果为复杂环境下的ME天线设计提供了定量指导，并展示了在微型无人平台和其他受限多物理场场景中的应用潜力。

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引用次数: 0

Magnetic property study of cryogenic permalloy for magnetic shielding in SHINE 低温坡莫合金在SHINE磁屏蔽中的磁性能研究

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2026-03-01 Epub Date: 2026-01-19 DOI: 10.1016/j.jmmm.2026.173836

Yongzhou He, Jian Dong

Cryogenic permalloy serves as the essential soft magnetic material for magnetic shielding of superconducting radio-frequency (SRF) cavities used in the cryomodules of advanced synchrotron radiation sources and hard X-ray free-electron lasers. Conventional permalloys exhibit severe degradation of permeability in liquid-nitrogen (LN₂) and sub-LN₂ environments, making them unsuitable for the increasingly stringent ultra-low-field requirements of SRF cavities. This work presents the design, fabrication, and systematic characterization of several composition-engineered permalloy variants developed specifically for magnetic shielding in the Shanghai High repetition-rate XFEL and Extreme light facility (SHINE) superconducting modules. Comprehensive magnetometric analyses demonstrate that the newly developed cryogenic permalloys maintain excellent soft-magnetic properties at both room temperature and 77 K, while also exhibiting a broad heat-treatment window and outstanding corrosion resistance. At LN₂ temperature, the initial permeability

μ_{i}

reaches 4

\times

10⁵–1

\times

10⁶ and the maximum permeability

μ_{m}

reaches 3

\times

10⁶–4

\times

10⁶—values that significantly surpass those of both conventional permalloys and existing cryogenic permalloys—thus fully meeting the demanding shielding-efficiency requirements of SHINE and similar SRF cavity systems.

低温坡莫合金是先进同步辐射源和硬x射线自由电子激光器低温模块中超导射频（SRF）腔磁屏蔽必不可少的软磁材料。传统的坡合金在液氮（LN2）和亚LN2环境中渗透性会严重退化，这使得它们不适合SRF腔日益严格的超低场要求。本研究介绍了几种复合工程坡莫合金变体的设计、制造和系统表征，这些变体专门用于上海高重复率XFEL和极光设备（SHINE）超导模块的磁屏蔽。综合磁强分析表明，新开发的低温坡莫合金在室温和77 K下都能保持优异的软磁性能，同时还表现出较宽的热处理窗口和优异的耐腐蚀性。在LN2温度下，初始磁导率μi达到4 × 105-1 × 106，最大磁导率μi达到3 × 106 - 4 × 106，大大超过了传统坡进合金和现有的低温坡进合金，完全满足了SHINE和类似SRF腔体系统对屏蔽效率的要求。

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引用次数: 0

Twist-tunable moiré magneto-Excitonic Polaritons at 2D ferromagnetic interfaces 二维铁磁界面上的扭可调谐磁激子

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2026-03-01 Epub Date: 2026-01-06 DOI: 10.1016/j.jmmm.2026.173812

Arash Vaghef-Koodehi , Mahmoud Nikoufard , Yaser Bahari

We present a theoretical investigation of moiré magneto-excitonic polaritons in twisted bilayer transition-metal dichalcogenide heterostructures interfaced with two-dimensional ferromagnets. By combining a full electromagnetic simulation based on time-domain finite-difference (FDTD) calculations with a microscopic exciton–magnon Hamiltonian derived from tight-binding theory, we reveal the emergence of strong hybridization between excitonic and magnonic modes mediated by the moiré superlattice potential. The coupling strength exhibits Rabi splitting up to ≈ 8 meV under moderate magnetic fields and maintains coherent hybridization up to 180 K for CrI₃ and 230 K for Fe₃GeTe₂ substrates. The hybrid mode shows pronounced valley-selective behavior with an intensity ratio of ∼8:1 (K:K′) and an ultrafast oscillation period in the terahertz (THz) range, corresponding to light–matter–spin coherence on the picosecond scale. These results uncover a controllable pathway to engineer moiré-assisted exciton–magnon coupling governed by twist angle, magnetic exchange, and gate bias, thereby providing a physical foundation for tunable spin-polarized quantum photonic and opto-magnonic devices. Beyond its fundamental implications for correlated moiré physics, this study delineates a realistic route toward THz-bandwidth, nonreciprocal, and valley-selective photonic interfaces operating at elevated temperatures—establishing moiré magneto-excitonics as a credible frontier for next-generation hybrid quantum materials.

我们提出了二维铁磁体界面的扭曲双层过渡金属双硫化物异质结构中moirir磁激子的理论研究。通过将基于时域有限差分（FDTD）计算的完整电磁模拟与由紧密结合理论推导的微观激子-磁振子哈密顿量相结合，我们揭示了由莫尔超晶格势介导的激子模式和磁振子模式之间强杂化的出现。耦合强度在中等磁场下显示出高达≈8 meV的Rabi分裂，并且在CrI₃和Fe₃GeTe₂衬底上保持高达180 K和230 K的相干杂化。混合模式显示出明显的谷选择行为，强度比为~ 8:1 （K:K’），在太赫兹（THz）范围内具有超快振荡周期，对应于皮秒尺度的光-物质自旋相干。这些结果揭示了一种可控的途径来设计由扭曲角、磁交换和栅极偏置控制的莫尔梅兹辅助激子-磁振子耦合，从而为可调谐自旋极化量子光子和光磁振子器件提供了物理基础。除了相关莫尔莫尔物理学的基本含义之外，本研究还描绘了在高温下工作的太赫兹带宽，非互反和谷选择性光子界面的现实路线-将莫尔莫尔磁激子学建立为下一代混合量子材料的可靠前沿。

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引用次数: 0

Microstructural evolution during aging process in 2:17-type SmCo sintered magnets with different iron content 不同铁含量的2:17型SmCo烧结磁体时效过程中的组织演变

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2026-03-01 Epub Date: 2026-01-24 DOI: 10.1016/j.jmmm.2026.173870

Shuai Wang , Chenchen Xu , Weixiao Hou , Hui Yong , Yu Wang , Jifan Hu

It is confirmed that the aging process to obtain excellent magnetic properties is different for the magnets with various Fe content, and the influence of isothermal aging duration and cooling rate on microstructure and magnetic properties of the magnets has been studied systematically. As the isothermal aging duration increases, the B_r of magnets with different Fe content decreases due to the increasing 1:5H phase. The isothermal aging duration is 4 h for the Sm(Co_balFe_0.227Cu_0.072Zr_0.023)_7.6 magnet (Magnet A, relatively low Fe content) to obtain optimal H_cj and H_k, which is shorter than that of the Sm(Co_balFe_0.263Cu_0.072Zr_0.023)_7.6 magnet (Magnet B): 8 h. The magnets that have undergone appropriate aged time exhibit complete cellular structure, high lamellar phase density and high Cu concentration at cell boundaries, which makes the magnets show high H_cj and H_k. It is also found that the magnet with lower Fe content exhibits a faster ordering transformation rate during the aging process. On the other hand, the optimal aging cooling rate required to achieve desirable magnetic properties varies with the Fe content in the magnets. At a cooling rate of 1.5 K/min, Magnet B with higher Fe content still maintains a high and homogeneous distribution of the peak Cu concentration at the cell boundaries, resulting in excellent magnetic properties. In contrast, a lower peak Cu concentration was observed in some cell boundaries of Magnet A under the same conditions, leading to the reduction of H_cj and H_k.

证实了不同铁含量的磁体获得优异磁性能的时效过程不同，并系统研究了等温时效时间和冷却速度对磁体组织和磁性能的影响。随着等温时效时间的延长，不同铁含量磁体的Br由于1:5H相的增加而降低。Sm(CobalFe0.227Cu0.072Zr0.023)7.6磁体（磁体A，铁含量相对较低）获得最佳Hcj和Hk的等温时效时间为4 h，短于Sm(CobalFe0.263Cu0.072Zr0.023)7.6磁体（磁体B）的等温时效时间为8 h。经过适当时效时间的磁体具有完整的胞体结构、较高的片层相密度和胞界处较高的Cu浓度，使得磁体具有较高的Hcj和Hk。在时效过程中，铁含量较低的磁体表现出更快的有序转变速率。另一方面，获得理想磁性能所需的最佳时效冷却速率随磁体中铁含量的不同而变化。在1.5 K/min的冷却速率下，铁含量较高的磁铁B在电池边界处仍然保持较高且均匀的Cu峰浓度分布，具有优异的磁性能。相反，在相同的条件下，磁铁a的某些细胞边界的Cu浓度峰值较低，导致Hcj和Hk的减少。

{"title":"Microstructural evolution during aging process in 2:17-type SmCo sintered magnets with different iron content","authors":"Shuai Wang , Chenchen Xu , Weixiao Hou , Hui Yong , Yu Wang , Jifan Hu","doi":"10.1016/j.jmmm.2026.173870","DOIUrl":"10.1016/j.jmmm.2026.173870","url":null,"abstract":"<div><div>It is confirmed that the aging process to obtain excellent magnetic properties is different for the magnets with various Fe content, and the influence of isothermal aging duration and cooling rate on microstructure and magnetic properties of the magnets has been studied systematically. As the isothermal aging duration increases, the <em>B</em><sub>r</sub> of magnets with different Fe content decreases due to the increasing 1:5H phase. The isothermal aging duration is 4 h for the Sm(Co<sub>bal</sub>Fe<sub>0.227</sub>Cu<sub>0.072</sub>Zr<sub>0.023</sub>)<sub>7.6</sub> magnet (Magnet A, relatively low Fe content) to obtain optimal <em>H</em><sub>cj</sub> and <em>H</em><sub>k</sub>, which is shorter than that of the Sm(Co<sub>bal</sub>Fe<sub>0.263</sub>Cu<sub>0.072</sub>Zr<sub>0.023</sub>)<sub>7.6</sub> magnet (Magnet B): 8 h. The magnets that have undergone appropriate aged time exhibit complete cellular structure, high lamellar phase density and high Cu concentration at cell boundaries, which makes the magnets show high <em>H</em><sub>cj</sub> and <em>H</em><sub>k.</sub> It is also found that the magnet with lower Fe content exhibits a faster ordering transformation rate during the aging process. On the other hand, the optimal aging cooling rate required to achieve desirable magnetic properties varies with the Fe content in the magnets. At a cooling rate of 1.5 K/min, Magnet B with higher Fe content still maintains a high and homogeneous distribution of the peak Cu concentration at the cell boundaries, resulting in excellent magnetic properties. In contrast, a lower peak Cu concentration was observed in some cell boundaries of Magnet A under the same conditions, leading to the reduction of <em>H</em><sub>cj</sub> and <em>H</em><sub>k</sub>.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"641 ","pages":"Article 173870"},"PeriodicalIF":3.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074399","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}

引用次数: 0

Magnetic carbon-nanoparticles behavior of biomorphic pyrolytic carbons 磁性碳纳米颗粒的生物形态热解碳行为

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2026-02-15 Epub Date: 2026-01-02 DOI: 10.1016/j.jmmm.2026.173811

V.V. Popov , T.S. Orlova , A.A. Spitsyn , D.A. Kirilenko , K.V. Dyakonov

Magnetic properties of biomorphic carbon-based materials obtained from birch-wood pyrolysis products using carbonization temperature of 700 °C with and without subsequent activation at 970 °C have been studied in a wide temperature range of 2–300 K in magnetic fields up to 140 kOe. It was found that biocarbon samples purified from volatile wood decomposition product (tar) during pyrolysis demonstrate diamagnetic behavior of magnetization at room temperature and paramagnetic at low temperatures, while in biocarbon samples with residual or specially introduced pyrolysis tar, a ferromagnetic component of magnetization is observed at room temperature. The analysis showed that ferromagnetism appears as a result of the formation of carbon magnetic nanoparticles during the carbonization of binding tar in the biocarbon. The magnitude of magnetization of such nanoparticles is comparable to the magnetization of nanoparticles formed by ferromagnetic metals that opens way to obtain porous magnetic biocarbon materials without ferromagnetic metal inclusions.

在高达140 kOe的磁场中，在2-300 K的宽温度范围内，研究了在700°C炭化温度下，经过970°C活化和不经过活化的桦木热解产物的生物形态碳基材料的磁性能。研究发现，热解过程中挥发性木材分解产物（焦油）纯化的生物碳样品在室温下表现出抗磁性磁化行为，在低温下表现出顺磁性，而在残余或特别引入热解焦油的生物碳样品中，在室温下表现出铁磁性磁化成分。分析表明，铁磁性是生物炭中结合焦油碳化过程中碳磁性纳米颗粒形成的结果。这种纳米颗粒的磁化强度与铁磁性金属形成的纳米颗粒的磁化强度相当，为获得没有铁磁性金属内含物的多孔磁性生物碳材料开辟了道路。

引用次数: 0

Phase stability and tunable structural, hyperfine, and magnetic properties of Sol–Gel FeNi nanoparticles 溶胶-凝胶FeNi纳米颗粒的相稳定性和可调结构、超细和磁性能

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2026-02-15 Epub Date: 2025-12-30 DOI: 10.1016/j.jmmm.2025.173792

M.A.R. Martinez , F.F.H. Aragón , L. León Félix , J. Mantilla , M.H. Sousa , M.C. Mathpal , J.F. Felix , J.A.H. Coaquira

In this study,

\sim

Fe₅₀Ni₅₀ powder alloys were synthesized successfully using the sol–gel method, followed by systematic thermal treatments up to 1000 °C in a reducing atmosphere (Ar-H

_{2}

). Synchrotron X-ray diffraction patterns indicate that the data are well modeled by face-centered cubic (FCC) FeNi phase. The stability of this phase was studied, revealing that as the temperature is increased, the unit cell volume changes, suggesting an enhancement in the migration of iron atoms. This migration alters the stoichiometry of the FeNi alloy, potentially shifting it beyond its nominal 50/50 composition. High-resolution TEM demonstrated the formation of the FeNi phase, which is in good agreement with the results obtained by XRD. Additionally, only a slight increase in crystalline particle size was observed. Magnetic characterization shows that thermal annealing strongly influences the magnetization. In particular, the sample annealed at 700 °C exhibits the highest magnetization and a Curie temperature

\sim

805 K, highlighting the role of thermal treatments in tuning the magnetic response. Zero-field cooling and field cooling measurements in the range 5–380 K further reveal irreversibilities above room temperature, attributed to the small particle size and strong interparticle interactions, which significantly affect the coercive field and overall magnetic behavior. These FeNi nanoparticles were characterized as magnetically soft materials. Mössbauer spectroscopy confirms the ferromagnetic behavior of the cubic FeNi phase as shown by XRD. Increasing the treatment temperature produces an increase in the hyperfine magnetic field, while the IS becomes more negative, which is primarily attributed to modifications in the s-electron density at the iron nuclei resulting from thermally induced electronic redistribution.

在本研究中，采用溶胶-凝胶法成功合成了~ Fe50Ni50粉末合金，然后在还原气氛（Ar-H2）中进行了高达1000°C的系统热处理。同步加速器x射线衍射图表明，面心立方（FCC） FeNi相能很好地模拟数据。研究了该相的稳定性，发现随着温度的升高，单位胞体积发生变化，表明铁原子的迁移增强。这种迁移改变了FeNi合金的化学计量，可能使其超出其标称的50/50组成。高分辨率透射电镜显示FeNi相的形成，这与XRD的结果吻合较好。此外，仅观察到晶体粒度略有增加。磁性表征表明，热退火对磁化强度有较大影响。特别是，在700°C退火的样品表现出最高的磁化强度和居里温度~ 805 K，突出了热处理在调节磁响应中的作用。在5-380 K范围内的零场冷却和场冷却测量进一步揭示了室温以上的不可逆性，这归因于小颗粒尺寸和强颗粒间相互作用，这显著影响了矫顽力场和整体磁行为。这些FeNi纳米颗粒被表征为磁性软材料。Mössbauer光谱分析证实了立方FeNi相的铁磁行为，如XRD所示。随着处理温度的升高，超细磁场增大，而IS变得更负，这主要是由于热诱导电子重分布导致铁核s电子密度的改变。

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引用次数: 0

Alloying effect on the magnetic and magnonic properties of a thin-film superlattice based on the magnetic semiconductor Ge1−xFex/Ge 合金化对基于磁性半导体Ge1−xFex/Ge的薄膜超晶格磁性和磁能谱的影响

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2026-02-15 Epub Date: 2025-12-29 DOI: 10.1016/j.jmmm.2025.173787

Marouan Karam, Atika Fahmi, Ahmed Qachaou, Mounir Fahoume, Ismail Benaicha, Jaouad Mhalla, Abderrahim Raidou, Mohamed Lharch

In this work, we investigate the effect of alloying on the magnetic properties of the semiconductor ferromagnetic Ge

_{1 - x}

Fe

_{x}

/Ge(001) superlattice. The system Hamiltonian is described within the localized-spin Heisenberg model. The excitation spectrum is calculated using linear spin-wave theory. A quantitative analysis of the experimental magnetization data reveals the existence of a spin reorientation transition (SRT) at the inflection temperature (

T = T_{r}

). To explain the behavior of this magnetization, we have developed a theoretical model based on the presence of a mixture of two magnon populations: quantum magnons and classical magnons. Furthermore, the agreement between the calculated and experimental magnetization curves is very satisfactory, enabling the determination of the key magnetic parameters of the system, namely,

J_{∥} (x)

,

J_{⊥} (x)

,

Δ (x)

, and

T_{r} (x)

.

在这项工作中，我们研究了合金对半导体铁磁Ge1−xFex/Ge（001）超晶格磁性能的影响。在局域自旋海森堡模型中描述了系统的哈密顿量。利用线性自旋波理论计算激发谱。对实验磁化数据的定量分析表明，在弯曲温度（T=Tr）下存在自旋重取向跃迁（SRT）。为了解释这种磁化行为，我们建立了一个基于两种磁振子种群混合物存在的理论模型：量子磁振子和经典磁振子。此外，计算和实验磁化曲线之间的一致性非常令人满意，从而可以确定系统的关键磁参数，即J∥(x), J⊥(x)， Δ(x)和Tr(x)。

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引用次数: 0

Investigation of magnetic phase transition and critical behavior in Cu2OSeO3 via magnetocaloric effect 利用磁热效应研究Cu2OSeO3的磁相变及临界行为

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2026-02-15 Epub Date: 2025-12-29 DOI: 10.1016/j.jmmm.2025.173791

Sudipta Mahana , Prasanta Kumar Behera , Keshab Chandra Prusty , Pronoy Nandi , Dinesh Topwal

Polycrystalline Cu₂OSeO₃ was synthesized via a solid-state reaction method, and its phase purity was confirmed through X-ray diffraction followed by Rietveld refinement. The compound features two distinct crystallographic copper sites: Cu(I) in a trigonal bipyramidal configuration and Cu(II) in a square pyramidal arrangement, present in a 1:3 ratio. This unique structure leads to complex magnetic interactions between the sites. Magnetic properties were investigated using DC magnetization and AC susceptibility measurements. The material exhibits a delicate balance of symmetric superexchange interactions, antisymmetric Dzyaloshinskii-Moriya (DM) interaction, magnetocrystalline anisotropy, and Zeeman energy, resulting in various intricate magnetic phases. These include fluctuation disorder (FD), helical, skyrmion mixed conical and tilted spiral, conical, field-polarized ferrimagnetism, and importantly, the skyrmion phase. Additionally, the magnetocaloric effect was studied through temperature-dependent heat capacity measurements under different magnetic fields. The findings indicate reasonable magnetic refrigeration capabilities, with maximum magnetic entropy changes of 2.23 J/kg·K and 4.25 J/kg·K at around 60 K for field changes of 4 T and 7 T, respectively. The corresponding maximum relative cooling powers are determined to be 67 J/Kg and 140 J/kg. The critical correlation was also investigated through the magnetocaloric effect, demonstrating 3D Heisenberg interaction above the paramagnetic to FD transition temperature (T_c), accompanied by short-range magnetic correlations. Furthermore, the universal behavior of the normalized magnetic entropy-change curve confirms the presence of a second-order magnetic phase transition near T_c under high magnetic fields.

采用固相反应法制备了多晶Cu2OSeO3，并通过x射线衍射和Rietveld精馏确定了其相纯度。该化合物具有两个不同的晶体铜位：Cu(I)在三角形双锥体结构中，Cu（II）在正方形锥体结构中，以1:3的比例存在。这种独特的结构导致了位点之间复杂的磁相互作用。通过直流磁化和交流磁化率测试研究了材料的磁性能。该材料表现出对称超交换相互作用、反对称Dzyaloshinskii-Moriya （DM）相互作用、磁晶各向异性和塞曼能量的微妙平衡，导致各种复杂的磁相。其中包括涨落无序态（FD）、螺旋态、斯基米子混合锥形和倾斜螺旋态、锥形态、场极化铁磁态，以及重要的斯基米子相。此外，通过测量不同磁场下的温度相关热容，研究了磁热效应。结果表明，在磁场变化为4 T和7 T时，在60 K左右，磁熵变化最大，分别为2.23 J/kg·K和4.25 J/kg·K。相应的最大相对冷却功率分别为67 J/Kg和140 J/Kg。通过磁热效应研究了临界相关性，证明了顺磁到FD转变温度（Tc）以上的三维海森堡相互作用，并伴有短程磁相关性。此外，归一化磁熵变曲线的普遍行为证实了高磁场下Tc附近存在二阶磁相变。

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