Journal of Magnetism and Magnetic Materials最新文献

{"title":"Theory of spin Seebeck effect activated by acoustic chiral phonons","authors":"Naoki Nishimura ,&nbsp;Takumi Funato ,&nbsp;Mamoru Matsuo ,&nbsp;Takeo Kato","doi":"10.1016/j.jmmm.2025.173386","DOIUrl":"10.1016/j.jmmm.2025.173386","url":null,"abstract":"<div><div>We theoretically explore the generation of spin current driven by a temperature gradient in a junction between a chiral insulator and a normal metal. Based on the gyromagnetic response induced by microscopic acoustic-phonon-mediated lattice rotation, we derive a formula for the spin current when a finite temperature difference is imposed between two ends of the sample. We clarify how the phonon-mediated spin current depends on the sample geometry, the thermal conductivity, the heat conductance at the interface, and the average temperature. Our formulation provides a microscopic foundation for the chiral-phonon-activated spin Seebeck effect without relying on magnetism or spin–orbit interactions.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"630 ","pages":"Article 173386"},"PeriodicalIF":3.0,"publicationDate":"2025-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144828001","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":"Optimization of process parameters for predicting surface roughness in the magnetorheological finishing of hollow cylindrical surfaces using a machine learning algorithm","authors":"Manish Kumar,&nbsp;Shrushti Maheshwari,&nbsp;Zafar Alam","doi":"10.1016/j.jmmm.2025.173407","DOIUrl":"10.1016/j.jmmm.2025.173407","url":null,"abstract":"<div><div>Achieving high-precision surface quality in nano-finishing processes requires effective optimization of process parameters. This requires a large dataset for which experimentation is cumbersome, and the obtained experimental data is of a non-linear and contains outliers. Therefore, for effective prediction of surface roughness with non-linear experimental data, robust prediction techniques are required. Henceforth, this study focuses on optimizing parameters for the newly developed magnetorheological finishing process for internal cylindrical surfaces using a Gaussian Process Regression (GPR) model integrated with Bayesian optimization. The GPR model served as a probabilistic surrogate to predict surface roughness with exceptional accuracy, achieving an R² = 0.99 and an overall prediction accuracy of 99%. The proposed GPR model achieved superior prediction accuracy for surface roughness, with a Root Mean Squared Error (RMSE) of 3.3089, a Mean Absolute Error (MAE) of 2.6402, and a Relative RMSE (RRMSE) of 0.0222. It outperformed other machine learning models, SVM, DNN, and ANN, by achieving the lowest MSE (10.9487), MAPE (1.84%), and highest correlation coefficient (CC = 99.49%) in the testing phase, demonstrating its robustness and generalization capability. Bayesian optimization was employed to effectively search for the best combination of parameters., identifying the optimal conditions for achieving a nano-level finish. The robustness and generalization capability of GPR model were verified through K-fold cross-validation. Hyperparameter optimization further enhanced the model’s performance, reducing errors, enabling reliable prediction and achievement of ultra-smooth surface. Optimal results were obtained with a tool rotational speed of 420 rpm, working gap of 0.8 mm, and reciprocating speed of 3 cm/s. Under these conditions, the internal surface roughness was drastically reduced to an impressive Ra = <span><math><mrow><mn>0</mn><mo>.</mo><mn>059</mn><mspace></mspace><mi>μ</mi><mi>m</mi></mrow></math></span>.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"630 ","pages":"Article 173407"},"PeriodicalIF":3.0,"publicationDate":"2025-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144809996","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":"Quantum and spin driven effects on acoustic wave dynamics in piezoelectric semiconductor plasma","authors":"Abhishek Yadav,&nbsp;Punit Kumar","doi":"10.1016/j.jmmm.2025.173431","DOIUrl":"10.1016/j.jmmm.2025.173431","url":null,"abstract":"<div><div>The influence of spin polarization, induced by the difference in concentration of spin-up and spin-down electrons produced under the influence of a magnetic field, on lattice ion vibrations-electron wave interactions, and the resulting amplification of acoustic waves, has been studied in spin polarised piezoelectric semiconductor quantum plasma. The dielectric permittivity of the high-density plasma medium has been evaluated through which the dispersion relation has been set up. The gain coefficient of acoustic waves has been obtained using the modified separate spin evolution quantum hydrodynamic (SSE-QHD) model for piezoelectric semiconductor plasma. The study shows that quantum effects, such as Fermi pressure and the quantum Bohm potential, lead to a reduction in wave frequency. In contrast, spin polarization results in an increase in wave frequency. Additionally, the presence of quantum effects significantly enhances acoustic gain as frequency rises. Spin polarization also contributes to a slight increase in acoustic wave amplification.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"630 ","pages":"Article 173431"},"PeriodicalIF":3.0,"publicationDate":"2025-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144809342","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 and thermal modulation of DC-AC electrical properties in Zn0.3Ni0.7Fe2O4 nanoparticles","authors":"Sarit Chakraborty ,&nbsp;Tanmoy Majumder ,&nbsp;Saurabh Kumar ,&nbsp;Sritama Roy","doi":"10.1016/j.jmmm.2025.173427","DOIUrl":"10.1016/j.jmmm.2025.173427","url":null,"abstract":"<div><div>In the pursuit of efficient magnetic nanoparticles for device applications, Zn_0.3Ni_0.7Fe₂O₄ nanoparticles were synthesized via a low-temperature pyrophoric reaction to explore their DC and AC electrical properties under varying magnetic fields and temperatures. Structural analysis using X-ray diffraction confirmed a single-phase spinel structure with an average crystallite size of ∼38 nm, while FE-SEM revealed a homogeneous surface morphology. EDX confirmed the elemental composition without impurities. DC electrical studies showed a ∼330 % enhancement in current at 20 V and 2.0 kOe, attributed to oxygen vacancies and improved charge carrier mobility. The current–voltage behavior exhibited finite short-circuit current and open-circuit voltage, indicating charge storage via interfacial polarization at grain boundaries. AC measurements revealed a high dielectric constant at low frequencies, governed by interfacial polarization, with a magnetodielectric effect of ∼14 % and a magnetoimpedance change of ∼−10.7 % at 2.0 kOe (200 Hz). Impedance spectroscopy and Nyquist plot modeling showed that grain and grain boundary contributions dominate the conduction process. Magnetic field application reduced resistance and increased capacitance, suggesting field-assisted conduction. Temperature-dependent studies indicated a transition from metallic to semiconducting behavior, supported by analysis of the real and imaginary parts of impedance. AC conductivity followed Jonscher’s power law, with small polaron hopping dominating at lower temperatures and large polaron hopping becoming significant beyond the transition, indicating thermally activated conduction. These results demonstrate the strong magnetoelectric coupling and conduction tunability of Zn_0.3Ni_0.7Fe₂O₄ nanoparticles, making them promising candidates for multifunctional device applications.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"630 ","pages":"Article 173427"},"PeriodicalIF":3.0,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144827961","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":"An improved experimental technique employing cavity perturbation to investigate the insulating properties of a few lossy materials at 8.5 GHz in X-band","authors":"S. Maiti ,&nbsp;A.K. Pradhan ,&nbsp;S.K. Biswas ,&nbsp;S. Gangopadhyay ,&nbsp;A. Banerjee ,&nbsp;P. Roy Chowdhury","doi":"10.1016/j.jmmm.2025.173429","DOIUrl":"10.1016/j.jmmm.2025.173429","url":null,"abstract":"<div><div>The insulating properties of cylindrical Teflon, Bakelite and Acrylic substrates have been investigated experimentally using a Q-choked single iris rectangular copper cavity resonator at 8.5 GHz. Subsequently a methodical simulation studies have been performed using ANSYS HFSS to rationalize the errors originated from the conventional experimental design for dielectric characterizations. The 3-D electromagnetic simulation studies are extensively used for the optimization of iris and Q-choke diameters. The simulated complex dielectric permittivity derived for five commonly used low loss dielectric materials at seven discrete frequencies within X-band demonstrate an optimum accuracy at 8.5 GHz when substrate diameter is restricted within 1.0–4.0 mm. Additionally, using the insulating properties of ferrite magnet (e.g., Y35) at distinct sample radius (<span><math><mrow><msub><mi>R</mi><mi>S</mi></msub><mo>≤</mo><mn>0.6</mn><mspace></mspace><mi>m</mi><mi>m</mi></mrow></math></span>) unvail the novelty of the proposed resonator. Moreover, a correction factor is added to the conventional perturbation formula to compensate the errors arisen due to any change in sample position from respective cavity centre. Both the simulation and experimental results of permittivity characteristics for the three specified materials of interest show even better agreement with the previous reports and standard specifications.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"630 ","pages":"Article 173429"},"PeriodicalIF":3.0,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144858239","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":"Automatic visual identification of defects by magnetic field imaging using alternating current field measurement technique","authors":"Jingkang Xiao ,&nbsp;Fengli Zhang ,&nbsp;Feng Qiu ,&nbsp;Jinjiang Wang","doi":"10.1016/j.jmmm.2025.173413","DOIUrl":"10.1016/j.jmmm.2025.173413","url":null,"abstract":"<div><div>Traditional electromagnetic testing methods rely on manual analysis of signals, resulting in low visual clarity and a propensity for human error. Therefore, this paper proposes an automatic defect recognition method based on alternating current field measurement (ACFM) technology, which achieves visual identification of defects by constructing images of distorted magnetic fields caused by the defects. The method integrates magnetic field interpolation imaging technology with image processing algorithms to improve visualization and enable automated defect recognition. First, an ACFM simulation model is established to analyze the relationship between the magnetic induction perpendicular to the specimen surface and the disturbances in the induced current at defect edges, thereby revealing the signal distribution patterns. On this basis, a magnetic field interpolation imaging technique is proposed to transform one-dimensional testing curves into two-dimensional magnetic field distribution images, and visual algorithms are incorporated to design automatic defect recognition rules. Defect quantification is achieved based on hue extremum analysis of the distorted magnetic field regions. Finally, the effectiveness of the method is verified on an ACFM experimental platform. The experimental results demonstrate robust multi-defect detection capability, achieving localization errors below 4 % and maximum recognition errors of less than 6 % for defect length. For depth estimation, the system leverages the Hue component of the magnetic field image, yielding a correlation coefficient exceeding 0.99 between the extracted Hue feature and the actual defect depth. The system also accurately resolves crack orientation and characterizes corrosion morphology, with all recognition errors maintained below 5 %. The proposed magnetic field image-based visual processing rules enable automated and highly accurate quantification of defect parameters, validating the method’s effectiveness in practical scenarios.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"630 ","pages":"Article 173413"},"PeriodicalIF":3.0,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144771229","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":"Controllable ferromagnetism in CoCl2 monolayer: Intrinsic bipolar ferromagnetic semiconductor","authors":"Xu-li Wang,&nbsp;Hua Chen,&nbsp;Jin Lv,&nbsp;Hai-shun Wu","doi":"10.1016/j.jmmm.2025.173414","DOIUrl":"10.1016/j.jmmm.2025.173414","url":null,"abstract":"<div><div>Intrinsic bipolar ferromagnetic semiconductor (BFMSs) monolayer materials with the unique spin and charge properties have become an ideal choice for exploring the next generation of high-speed, low-power and non-volatile memory devices. In this work, using first-principles calculations, we predicted that the CoCl₂ monolayer is a stable out-of-plane BFMSs with a large indirect spin band gap (2.653  eV) and its perpendicular magnetocrystalline anisotropic energy (PMAE/0.333 meV per unit cell) are mainly originate from the couplings of Co-d_yz/d_z² orbitals thorough L_x in the different spin channels and the Co-d_xz/d_yz orbitals thorough L_z in the same spin channels. And after breaking the mirror symmetry, its Janus monolayer CoClBr shows a stronger ferromagnetism, a higher Curie temperature (Tc/210 K) and a novel half-semiconductor (HSCs) property. In addition, the CoCl₂ monolayer’s Tc and PMAE can be markedly improved under the compressive strain. For example, at −2% and −6% strains, Tc and PMAE can reach maximum values of 200 K and 0.436 meV, respectively. Besides, under the electronic doping, its Tc can also be enhanced and there will be a transition from BFMS to half-metal and then to metal. These findings indicate that our work offers a candidate material for spintronics devices.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"630 ","pages":"Article 173414"},"PeriodicalIF":3.0,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144779386","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":"Comment on “Finite element analysis on entropy generation in MHD Iron(III) Oxide-Water NanoFluid equipped in partially heated fillet cavity” [Journal of Magnetism and Magnetic Materials 565 (2023) 170269]","authors":"Mohammed Sarfaraz Hussain ,&nbsp;S. Mohammed Ibrahim ,&nbsp;Sumon Saha","doi":"10.1016/j.jmmm.2025.173418","DOIUrl":"10.1016/j.jmmm.2025.173418","url":null,"abstract":"<div><div>This comment critiques a study cited in the aforementioned publication, highlighting its errors and omissions. We identify areas lacking detail and propose corrections to enhance the accuracy of the research. Our objective is to bolster the reliability of the original work through clear explanations and suggested fixes.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"630 ","pages":"Article 173418"},"PeriodicalIF":3.0,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144771228","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":"Research of the levitation force second leap phenomenon in second-order levitation force experiments of magnetic fluids with sidewall constraint","authors":"Tingxin Liu ,&nbsp;Jie Yao ,&nbsp;Decai Li ,&nbsp;Xinyu Zhao ,&nbsp;Hui Li","doi":"10.1016/j.jmmm.2025.173411","DOIUrl":"10.1016/j.jmmm.2025.173411","url":null,"abstract":"<div><div>The levitation force of magnetic fluids is a critical parameter determining the performance of devices such as dampers, sensors, bearings, and actuators. It has been observed that when a magnetic fluid is underfilled in a container, wall confinement induces a quadratic acceleration in the levitation force with increasing fluid mass—a phenomenon termed the “second leap”. Nevertheless, the underlying physical mechanism remains inadequately explained. This study derives a computational formula for the levitation force on a permanent magnet based on the static equilibrium equations and Bernoulli’s equation, establishing a functional relationship between the levitation force, surface tension, and magnetic field strength. Through comparative analysis of experimental and simulation results, we systematically investigate the influence of sidewall confinement on the levitation force, validate its variation, and rule out the contribution of the surface tension. Ultimately, we demonstrate that the “second leap” of the levitation force arises from the combined effects of increased gravitational potential energy and reduced magnetic field strength at the magnetic fluid-air boundary.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"630 ","pages":"Article 173411"},"PeriodicalIF":3.0,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144771227","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":"Effect of microwave sintering on phase evolution and magnetic behavior of barium hexaferrite","authors":"S. Bharadwaj ,&nbsp;Y. Kalyanalakshmi ,&nbsp;T. Sai Santoshi","doi":"10.1016/j.jmmm.2025.173419","DOIUrl":"10.1016/j.jmmm.2025.173419","url":null,"abstract":"<div><div>A systematic study on the effect of microwave sintering on structural and magnetic behavior of M-type barium hexaferrite prepared using sol–gel method is presented. The powders were calcined at 700 °C/3 hrs and then a single pellet has been sintered at different temperatures of 750 °C, 850 °C, 950 °C and 1050 °C with 30 min as holding time in a microwave furnace. X-ray diffraction studies and Rietveld analysis confirms the presence of hexaferrite phase along with α-Fe₂O₃ phase and this additional phase vanishes for 950 °C and 1050 °C sintering temperatures. The Goodness of fit and χ² found from Rietveld analysis further confirms the purity of the phase. Grain size increases systematically with microwave sintering conditions and ranges between 159 nm and 225 nm. The magnetic parameters such as remanent magnetization, saturation magnetization and coercivity increases with microwave sintering temperature up to 950 °C but slightly drops for 1050 °C sample. These variations in the magnetic behavior of microwave sintering hexaferrites could be attributed to controlled grain size effects and the iron ion distributions at various available sites.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"630 ","pages":"Article 173419"},"PeriodicalIF":3.0,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144771304","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}