Journal of Magnetism and Magnetic Materials最新文献

{"title":"The temperature-dependent anomalous Hall effect in CoO/Pt bilayers","authors":"Kaibin Wen ,&nbsp;Tanzhao Zhang ,&nbsp;Ye Liu ,&nbsp;Yong Wu ,&nbsp;Kangkang Meng ,&nbsp;Jikun Chen ,&nbsp;Xiaoguang Xu ,&nbsp;Yong Jiang","doi":"10.1016/j.jmmm.2025.173333","DOIUrl":"10.1016/j.jmmm.2025.173333","url":null,"abstract":"<div><div>In this study, we systematically investigate the temperature evolution of the anomalous Hall effect (AHE) in CoO/Pt heterostructures. A characteristic sign inversion of the AHE emerges at 140 K, concomitant with a progressively enhanced positive spin Hall magnetoresistance (SMR) as temperature decreases from 300 K to 50 K. These findings indicate that both the magnetic proximity effect (MPE) and the spin Hall effect (SHE) contribute to the AHE with opposite sign, and uncompensated spins are present at the CoO/Pt interface. By introducing Co³⁺ at the CoO/Pt interface through high-oxygen-pressure annealing, the anomalous Hall resistance R_AHE is enhanced by an order of magnitude, attributed to the strengthened MPE. Furthermore, the competition between SHE and MPE also brings a sign change of the anisotropic magnetoresistance (AMR). Our results provide insights into the origin of AHE in antiferromagnetic insulator/heavy metal bilayers.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173333"},"PeriodicalIF":2.5,"publicationDate":"2025-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144514075","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":"Preparation of self-supporting flexible NiFe2O4 fibers and their adsorption performance for Pb(II)","authors":"Shuying Shi ,&nbsp;Zitao Guo ,&nbsp;Zetao Liu ,&nbsp;Ailin Yang ,&nbsp;Yongshuang You ,&nbsp;Long jiang ,&nbsp;Hao deng ,&nbsp;Pengfei Gao","doi":"10.1016/j.jmmm.2025.173327","DOIUrl":"10.1016/j.jmmm.2025.173327","url":null,"abstract":"<div><div>Magnetic fibers are ideal adsorbent material, the fibers have large aspect ratio, entangled with each other, do not agglomerate in water, magnetic materials can be magnetically separated, so magnetic fibers have the advantage of not agglomerating in water, easy to separate, more suitable for use as an adsorbent. The most commonly used methods for preparing NiFe₂O₄ fibers were direct electrospinning and surface loading. Whether using NiFe₂O₄ as a filler for direct electrospinning or loading it onto fibers, there are issues with limited NiFe₂O₄ content and uneven loading. Compared to commonly used direct electrospinning and surface loading, we developed a simple sol–gel method to prepare the precursor spinning solution, then prepared the magnetic NiFe₂O₄ fibers with excellent flexibility through electrospinning, and applied it to the adsorption of Pb (II) for the first time. The spinning solution was synthesized using iron sources, nickel sources and citric acid, the iron and nickel ions coordinated with carboxyl group according to the monodentate coordination. The flexible NiFe₂O₄ fibers exhibited a saturation magnetization of 18.2 emu/g. Specific surface area of the flexible NiFe₂O₄ fibers was 13.443 m²/g and total pore volume of the magnetic NiFe₂O₄ fibers was 0.074 cm³/g. In the adsorption experiment, The NiFe₂O₄ fibers demonstrated a maximum Pb(II) adsorption capacity of 49.53 mg/g. Due to the self-supporting and non-agglomeration advantages of the fiber structure in solution and the maximum adsorption capacity of the NiFe₂O₄ fibers synthesized in this study for Pb(II) exceeded that of most previously reported NiFe₂O₄ adsorbents. Flexible magnetic fibers provided a new solution for simultaneously improving the adsorption capacity of pollutant and achieving rapid magnetic separation, becoming another new material for expanding applications in the field of wastewater treatment.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173327"},"PeriodicalIF":2.5,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144534906","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":"First-principles study of the mechanism of ZnO magnetism in fibrillar zinc ore by zinc vacancies","authors":"Qingyu Hou ,&nbsp;Hailan Li ,&nbsp;Wen Ma ,&nbsp;Zhenchao Xu","doi":"10.1016/j.jmmm.2025.173331","DOIUrl":"10.1016/j.jmmm.2025.173331","url":null,"abstract":"<div><div>Currently, the influence of zinc (Zn) vacancies on the magnetic mechanism of fibrillar zincite ZnO (misjudgment from literature: J. Magn. Magn. Mater. 603 [2024] 172227) is controversial. To solve this problem, this study investigates the effect of Zn vacancies on the magnetic mechanism of fibrillated ZnO by using a first-principles density functional theory + Hubbard U approach, which shows that Zn vacancies are more likely to form in ZnO under oxygen-rich conditions than under Zn-rich conditions. The O¹^-–2p state with spin polarization is the source of the magnetic properties of the Zn₃₅O₃₆ system. Unlike the O²^-–2p state without spin polarization, the spin-polarized O¹^-–2p state has the dual property of localized and roaming electrons (acceptor and donor). The spin-polarized O¹^-–2p states agree with the experimental results. This model is expected to elucidate the magnetic mechanism of similar cationic vacancies in fibrillar ZnO structured semiconductors.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173331"},"PeriodicalIF":2.5,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144523300","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":"Broadband ferromagnetic resonance in Ni-Mn-Ga single crystal","authors":"Luděk Kraus,&nbsp;Denys Musiienko,&nbsp;Martin Kempa,&nbsp;Jaroslav Čapek","doi":"10.1016/j.jmmm.2025.173330","DOIUrl":"10.1016/j.jmmm.2025.173330","url":null,"abstract":"<div><div>We present a broadband ferromagnetic resonance study in single crystalline Ni₅₀Mn_28.1Ga_21.9 in the temperature range from room temperature to 120 °C in which the transformation from martensite to austenite phase takes place. Our measurements demonstrate that a large change (an order of magnitude) in the magnetocrystalline anisotropy at the martensitic phase transformation results in a sharp change of the resonance magnetic field. In a single variant martensite phase, the resonance fields satisfy the Kittel’s resonance condition for a thin film with the gyromagnetic factor <em>g</em> = 2.0. With the magnetic field parallel to the easy c-axis of the single variant martensite, the resonance is observed only for frequencies larger than 22 GHz. For the multivariant martensite case, the magnetic coupling between the twin variants can be taken into account for the satisfactory Kittel’s fit. We observe a weak magnetocrystalline anisotropy in the austenite phase, just above the reverse martensite transformation, comparable to the previous reports based on different magnetic measurements.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173330"},"PeriodicalIF":2.5,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144523302","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 hysteresis behavior of mixed spin (3/2, 7/2) systems on decorated triangular lattices: a mean field approximation","authors":"Aqeel Raad Ghafel","doi":"10.1016/j.jmmm.2025.173286","DOIUrl":"10.1016/j.jmmm.2025.173286","url":null,"abstract":"<div><div>We have researched ornamented ferrimagnetic mixed spin triangular systems using the molecular mean-field approximation. The study analyzed the outcomes based on the Blume-Capel Ising model. The research report looks at how crystal fields and outside magnetic fields affect ferrimagnetic devices with triangular lattices that are decorated with both spin-3/2 and spin-7/2 magnets. The report highlights the positioning of spin-3/2 ions at the nodes and the presence of six additional spin-7/2 ions in the vicinity of the lattice. One can achieve superparamagnetic properties by altering the exchange interactions using various crystal fields or external magnetic fields. New research shows that mixed spin triangular decorated ferrimagnets show superparamagnetism at different values while keeping the same D_A/|J₂| = 8 and D_B/|J₂| = −11. For mixed spin triangular lattices, J₁ = −0.5 and J₂ = 1. In addition, we have acquired the individual hysteresis loops for different physical parameters in the magnetic system under investigation, including single, double, and triple loops.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173286"},"PeriodicalIF":2.5,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144514071","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":"Magneto-dielectric composites synthesized using industrial waste","authors":"Sunil Kumar ,&nbsp;Shiffali Middha ,&nbsp;Sajan Masih ,&nbsp;Arshdeep Kaur ,&nbsp;Jaswinder Pal ,&nbsp;Norah Alhokbany ,&nbsp;Jahangeer Ahmed ,&nbsp;Gurpreet Singh ,&nbsp;López-García ,&nbsp;Satvir Singh ,&nbsp;Nitin Tandon ,&nbsp;Indu Sharma ,&nbsp;Arvind Kumar Sharma ,&nbsp;Anupinder Singh","doi":"10.1016/j.jmmm.2025.173306","DOIUrl":"10.1016/j.jmmm.2025.173306","url":null,"abstract":"<div><div>Coal Ash (CA) is an industrial waste procured from brick klin as waste obtained during the firing of raw bricks using rock coal, whereas BaTiO₃ (BT) &amp; KNaNbO₃ (KNN) well well-known ferroelectric perovskites synthesized in the laboratory using conventional solid solution approach. Multiferroic composites of _0.5Coal Ash-_0.5BaTiO₃ &amp; _0.5Coal Ash-_0.5KNaNbO₃ have been synthesized by mechanical mixing approach of Coal Ash collected from brick clan and as-synthesized BaTiO₃ &amp; KNaNbO₃. Structural phases present in Coal Ash have been analyzed according to metal ions confirmed from energy dispersive X-ray spectroscopy whereas diffraction peaks correspond to the tetragonal phase of BaTiO₃ and monoclinic phase of KNaNbO₃ in prepared composites of CA &amp; BT, KNN confirmed the successful synthesis of ceramic composites mentioned above. Morphological analysis has been carried out by scanning the surface of sintered pellets using an electron microscope, whereas energy dispersive spectroscopy (EDS) gives details of different elements present in studied samples. S-shaped magnetic hysteresis (Magnetization vs. Magnetic field hysteresis) manifests magnetic ordering in composites of Coal Ash &amp; non-magnetic ferroelectric BT &amp; KNN. The magnetic behavior of ceramic composites mainly due to different magnetic particles were present during coal combustion confirmed from x-ray diffraction analysis as well as presence of Fe metal ion confirmed from EDS spectroscopy. ε’ &amp; ε“ and σ_ac vs frequency evident for enhanced dielectric and conducting properties of multiferroic composites by processing Coal Ash with BT &amp; KNN and ‘α’ (Obtained from Fitting of Dielectric data) determined the deviation in dielectric behavior of ceramic composites from normal Debye behavior. The change in the value of dielectric permittivity in the presence and absence of a magnetic field stamped for the presence of magneto-dielectric response in _0.5Coal Ash-_0.5BaTiO₃ &amp; _0.5Coal Ash-_0.5KNaNbO₃ multiferroic composites.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173306"},"PeriodicalIF":2.5,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144490467","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":"Steady high-frequency antiskyrmion oscillator with anisotropic Dzyaloshinskii-Moriya interaction","authors":"Xuefeng Wu","doi":"10.1016/j.jmmm.2025.173324","DOIUrl":"10.1016/j.jmmm.2025.173324","url":null,"abstract":"<div><div>Magnetic skyrmions have garnered significant interest in recent years due to their potential applications in spintronic devices, such as spin-torque nano-oscillators (STNOs) and racetrack memory. However, the development of skyrmion-based STNOs has been hindered by their sub-GHz operational frequencies and propensity for annihilation under high current densities. In this study, stable antiskyrmion auto-oscillations in nanodisk geometries driven by spinpolarized currents enabled by anisotropic Dzyaloshinskii-Moriya interaction (DMI) were demonstrated. Through systematic comparisons of isotropic and anisotropic DMI systems, we uncover distinct topological stabilization mechanisms and current–density-dependent dynamics. At intermediate current densities (10–15 × 10¹¹ A·m⁻²), antiskyrmions exhibit a hybrid breathing-rotational mode, achieving oscillation frequencies of 9.66 GHz (in-plane) and 38.8 GHz (out-of-plane), with a robust frequency ratio of 3.9–4.1. Notably, antiskyrmions sustain current densities up to 400 % of the annihilation thresholds for conventional skyrmions, attributed to their unique chirality-dependent force equilibration. The tangential velocity of antiskyrmions reaches 587 m/s at 15 × 10¹¹ A·m⁻², governed by competing dependencies on current density and size contraction. These findings establish antiskyrmion-based STNOs as promising platforms for high-frequency, low-power spintronic applications, overcoming critical limitations of conventional skyrmion systems.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173324"},"PeriodicalIF":2.5,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144517952","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":"Impact of charge stripes on magnetization processes in rare-earth tetraborides","authors":"Pavol Farkašovský","doi":"10.1016/j.jmmm.2025.173284","DOIUrl":"10.1016/j.jmmm.2025.173284","url":null,"abstract":"<div><div>We examine the impact of charge stripes on magnetization processes in rare-earth tetraborides within a complex model which takes into account the electron and spin subsystem as well as the coupling (of the Ising type) between both subsystems. The charge stripes in this model are induced by adding the phenomenological, spatially varying local potential <span><math><msub><mrow><mi>V</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span>. Our assumption is based on a comparison of structural and electronic similarities between the rare-earth tetraborides and rare-earth hexaborides/dodecaborides, where such charge stripes (as a consequence of the Jahn–Teller effect) were experimentally observed. It is shown that the form and intensity of local potential <span><math><msub><mrow><mi>V</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span> (the type of charge stripes) have dramatic impact on the stability of individual plateaus on magnetization curves. The largest effects have been observed for the periodic potential forming the full charge stripes alternating with chessboard charge stripes. This type of charge ordering leads to magnetization curves with extremely simple structure consisting of only two main magnetization plateaus with fractional magnetization m=1/2 and m=1/3, the stability regions of which depend strongly on the model parameters. It is shown that with increasing intensity of local potential <span><math><msub><mrow><mi>V</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span> the 1/2 plateau (1/3 plateau) is generally stabilized (suppressed) and this effect is further enhanced by increasing spin-electron coupling leading to total disappearance of the 1/3 plateau, exactly as is observed in TmB<span><math><msub><mrow></mrow><mrow><mn>4</mn></mrow></msub></math></span> and ErB<span><math><msub><mrow></mrow><mrow><mn>4</mn></mrow></msub></math></span>. It should be noted that although charge stripes are introduced here ad hoc, the fact that our picture of magnetization processes is fully consistent with experimental measurements in TmB<span><math><msub><mrow></mrow><mrow><mn>4</mn></mrow></msub></math></span> and ErB<span><math><msub><mrow></mrow><mrow><mn>4</mn></mrow></msub></math></span> indicates that this assumption is reasonable and could serve as motivation for experimental physicists to find such a type of charge ordering in these materials.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173284"},"PeriodicalIF":2.5,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144490466","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":"Electron spin resonance study of the van der Waals ferromagnet Fe5GeTe2","authors":"Yang Yang ,&nbsp;Fanying Meng ,&nbsp;Wei Liu ,&nbsp;Jingxin Li ,&nbsp;Jing Zhang ,&nbsp;Jiyu Fan ,&nbsp;Chunlan Ma ,&nbsp;Min Ge ,&nbsp;Li Pi ,&nbsp;Zhe Qu ,&nbsp;Lei Zhang","doi":"10.1016/j.jmmm.2025.173251","DOIUrl":"10.1016/j.jmmm.2025.173251","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The van der Waals (vdW) material Fe&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;GeTe&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; is a promising candidate for spintronic applications due to its high Curie temperature (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;) and easily controllable properties. In this study, we thoroughly investigate the magnetic anisotropy of Fe&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;GeTe&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; single crystals using magnetization and electron spin resonance (ESR) techniques. We find that the magnetization for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; is stronger than that for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;c&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; below &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mo&gt;∼&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;100 K, exhibiting a weak easy-plane anisotropy (EPA). This EPA is significantly enhanced in the temperature range of &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mo&gt;&lt;&lt;/mo&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mo&gt;&lt;&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, indicating an enhanced EPA effect. Meanwhile, the ESR spectra show weak intensity below &lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; while significantly anisotropic signals are observed in the enhanced EPA region, with stronger ESR intensity for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; compared to that for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;c&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. The resonance fields (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;) for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;c&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; display opposite trends. The resonance field &lt;span&gt;&lt;math&gt;&lt;msubsup&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;/math&gt;&lt;/span&gt; for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; shifts toward lower fields, while &lt;span&gt;&lt;math&gt;&lt;msubsup&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;c&lt;/mi&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;/math&gt;&lt;/span&gt; for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;c&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; moves toward higher fields upon cooling. This contrary trends of &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;c&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; are attributed to the effects of ","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173251"},"PeriodicalIF":2.5,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144471055","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 anisotropy of Co/h-BN heterostructures: First principles calculations","authors":"Dian Putri Hastuti ,&nbsp;Yukie Kitaoka ,&nbsp;Hiroshi Imamura","doi":"10.1016/j.jmmm.2025.173282","DOIUrl":"10.1016/j.jmmm.2025.173282","url":null,"abstract":"<div><div>Magnetic anisotropy (MA) is an important characteristic of magnetic films for the application of spintronics devices such as magnetoresistive random access memories (MRAMs) and magnetic field sensors. Perpendicular MA is more suitable for MRAM, while in-plane MA is better for magnetic field sensor applications. Hexagonal boron nitride (h-BN) has recently attracted much attention as an efficient tunnel barrier for magnetic tunnel junctions with hexagonal symmetry. In this study, the magnetic anisotropy of a Co thin film deposited on h-BN is theoretically investigated using first-principles calculations. It is observed that a substantial perpendicular magnetocrystalline anisotropy (MCA) of the order of 1 mJ/m² is achieved for the film comprising 1 <span><math><mo>∼</mo></math></span> 5 Co atomic layers. The buckled structure of the h-BN layer at the interface is found to enhance the perpendicular MCA. The magnetic dipole energy is also calculated and is found to cause the in-plane MA for the films comprising 2 <span><math><mo>∼</mo></math></span> 5 Co atomic layers. The film comprising a monoatomic Co layer is found to be perpendicularly magnetised with an anisotropy constant of 1.68 mJ/m² and a voltage-controlled MA coefficient of -175 fJ/Vm, which are of the same order as those for the Fe/MgO film. In the case of in-plane magnetised films comprising 2 <span><math><mo>∼</mo></math></span> 5 Co atomic layers, the MA energy is found to be independent of the in-plane angle, which is a preferable characteristic for sensor applications. The results provide fundamental insights into the MA of Co/h-BN heterostructures and a foundation for developing voltage-controlled MRAM and magnetic field sensors based on this material.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"629 ","pages":"Article 173282"},"PeriodicalIF":2.5,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144534923","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}