Journal of Magnetism and Magnetic Materials最新文献

{"title":"Effect of precursor state on the formation of triphase (SmCo7 + SmCo3)/Fe(Co) magnets","authors":"Jieqiong Gao,&nbsp;Xiaohong Li,&nbsp;Tiancong Li,&nbsp;Li Lou,&nbsp;Yingxin Hua,&nbsp;Jinyi Wang,&nbsp;Yiran Li,&nbsp;Defeng Guo","doi":"10.1016/j.jmmm.2024.172666","DOIUrl":"10.1016/j.jmmm.2024.172666","url":null,"abstract":"<div><div>The combination of fabrication of a precursor and subsequent thermal treatments is an effective strategy for crafting multi-phase SmCo-based nanocomposite magnets. However, a comprehensive understanding of the effect of precursor state on the formation of multiphase magnets has yet to be fully explored. In this study, Sm(CoFeCuZr)/Fe(Co) of precursors were prepared via mechanical alloying. The precursor state was tailored by adjusting the ball milling process, as well as the content and composition of soft magnetic phase. The amorphization degree of the SmCo phase, the atomic ratio of Sm:Co in the SmCo alloy, and the content of Fe(Co) in the precursor increase with the increasing ball milling time, the increase in the content of the soft phase and the proportion of Fe within the soft phase. And this resulted in an increase in the content of Fe(Co) and SmCo₃ phases but a decrease in the content of SmCo₇ phase in samples annealed at 400–720 °C. This further led to an increase in the saturation magnetization and a decrease in the coercivity of the triphase (SmCo₇ + SmCo₃)/Fe(Co) magnet. The mechanisms responsible for the precursor state control and the formation of the triphase magnet were investigated.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"612 ","pages":"Article 172666"},"PeriodicalIF":2.5,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A magnetically controlled bio-inspired cobweb soft robot based on structural topology optimization","authors":"Yizhe Zhu,&nbsp;Yuchen Jin,&nbsp;Zewen Gu,&nbsp;Da Zhao,&nbsp;Jianlin Liu","doi":"10.1016/j.jmmm.2024.172649","DOIUrl":"10.1016/j.jmmm.2024.172649","url":null,"abstract":"<div><div>Magnetically controlled micro-soft robots have been widely used in precise drug delivery and treatment of the gastrointestinal tract due to their advantages of high flexibility, environmental adaptability and non-contact control. Current micro-soft robots usually employ simple configurations and homogeneous materials, which limits their deformation and movement capacities. Therefore, it is of great significance to make a comprehensive investigation on the properties of key elastic structures of micro-soft robots with complex configurations. In the present work we conduct a systematic study on the design, preparation, experiments and simulations of the common disc-shaped robot and the proposed bio-inspired cobweb robot. Firstly, the topology optimization strategies are developed to design the configuration of the bio-inspired cobweb robot. Then, two kinds of robots are prepared by the mold manufacturing method of mixing NdFeB particles and silica gel solution in a certain proportion and pouring. Next, the magnetic control deformation experiments on these two kinds of robots are carried out, and the corresponding force-magnetic coupling model is established. The simulation and experimental results of the longitudinal and lateral displacement and the deflection on a specific path are compared and analyzed, which validates the accuracy of the simulation model. Finally, based on the developed numerical model, the effects of different residual magnetization and different magnet positions of the driving force of the cobweb structure are further predicted. The results indicate that the topologically optimized cobweb robot presents better deformation and movement capacities under the same size. These findings shed new light on engineering soft robots with complicated configurations and improved capacity than existing soft robots.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"612 ","pages":"Article 172649"},"PeriodicalIF":2.5,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660681","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":"Textured CoZn-18H hexaferrite with enhanced Snoek’s product and suppressed magnetic loss","authors":"Donglin He ,&nbsp;Liangrui Tan ,&nbsp;Peng Wang ,&nbsp;Zhibiao Xu ,&nbsp;Qinglin Li ,&nbsp;Tao Wang","doi":"10.1016/j.jmmm.2024.172663","DOIUrl":"10.1016/j.jmmm.2024.172663","url":null,"abstract":"<div><div>Modern communications have created a great demand of magneto-dielectric functional materials having low loss and high permeability properties under the sub-6 GHz band. CoZn-18H planar hexagonal ferrites with strong magnetic anisotropy are more promising in meeting these requirements than that of traditional ferrites. The textured CoZn-18H hexagonal ferrites were synthesized by the reactive templated grain growth (RTGG) method to obtain high magnetic resonance frequency without sacrificing permeability. The layered texture composed of flaky hexagonal particles with a high aspect ratio played an important role in obtaining high permeability and high magnetic resonance frequency. The permeability <span><math><mrow><msup><mrow><mi>μ</mi></mrow><mo>′</mo></msup></mrow></math></span>, magnetic loss tangent tan δμ, and performance factor (<em>PF</em>) of the textured CoZn-18H hexagonal ferrite with the highest Snoek’s product (<em>SP</em> = 6.99 GHz) under 3.41 GHz were 1.66, 0.10, and 56.61 GHz, respectively. Compared with the traditional pure dielectric substrate, a planar inverted F antenna (PIFA) working at 3.0 GHz with a miniaturization rate of 18.1 % was simulated based on the textured CoZn-18H hexagonal ferrite. These results demonstrated that the method of preparing textured CoZn-18H hexagonal ferrites without the application of a magnetic field was effective and revealed the potential of textured planar hexagonal ferrites synthesized by the RTGG method of high-frequency and low-loss applications.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"612 ","pages":"Article 172663"},"PeriodicalIF":2.5,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660677","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":"Design and performance analysis of a vibration energy harvesting magnetorheological damper","authors":"Guoliang Hu ,&nbsp;Weizheng Lei ,&nbsp;Xingsheng Xi ,&nbsp;Tiannan Xu ,&nbsp;Tongfei Tian","doi":"10.1016/j.jmmm.2024.172664","DOIUrl":"10.1016/j.jmmm.2024.172664","url":null,"abstract":"<div><div>Magnetorheological (MR) dampers have a promising application in vehicle semi-active suspension system, but the direct application of MR dampers in vehicle semi-active suspension system inevitably requires a large amount of electrical energy from the on-board battery and there will be a power failure problem. At the same time, mechanical energy is converted into heat due to the friction between the cylinder and the damper piston of the MR damper. In order to avoid excessive energy waste and realize the self-powered supply of the MR damper to a certain extent, a new vibration energy harvesting MR damper (VEHMRD) is developed in this paper. First, energy harvesting, damping force and self-powered mathematical models are established. Then, the structural parameters of the proposed VEHMRD are designed, and the multi-objective water-cycle algorithm is applied to find out the optimal parameters of the proposed MR damper. Power generation and damping performance are simulated using Comsol software. Finally, a prototype is fabricated, and the power generation, damping force, and self-power ability of the VEHMRD are also tested. The experimental results are also compared with the simulated ones. The results show that the experimental induction voltage is lower than the simulated one with an error of about 15 %. The difference between the experimental damping force and the simulated damping force is small, with an error within 6 %, and the maximum damping force is about 1800 N at an applied current of 1.75A. When the collected electric energy is rectified and supplied to the MR damper, the damping force can reach over 400 N. The developed VEHMRD has a higher vibration energy harvesting capability. When powered by an external power source, the damping performance of the proposed MR damper is good. In addition, it can provide a certain damping force even when self-powered.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"612 ","pages":"Article 172664"},"PeriodicalIF":2.5,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660803","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 atomic substitution on the structural stability and half-metallicity of Fe2-xCrxCoSi (x = 0 to 1) alloys","authors":"Subrata Biswas,&nbsp;Perumal Alagarsamy,&nbsp;Ananthakrishnan Srinivasan","doi":"10.1016/j.jmmm.2024.172648","DOIUrl":"10.1016/j.jmmm.2024.172648","url":null,"abstract":"<div><div>Bulk Fe_2-<em>_x</em>Cr<em>_x</em>CoSi (<em>x</em> = 0, 0.25, 0.5, 0.75, and 1) Heusler alloys have been prepared by arc melting method. Alloys with 0 ≤ <em>x</em> ≤ 0.75 show a highly ordered phase pure <em>XA</em> structure. However, 17 % of an impurity (<em>A</em>15 phase) was detected in the alloy with <em>x</em> = 1. The saturation magnetization (<em>M</em>_s) and Curie temperature (<em>T</em>_C) decreased linearly with an increase in Cr content for alloys with <em>x</em> ≤ 0.75. <em>M</em>_s measured at 5 K followed the Slater–Pauling rule for half-metals. <em>Ab initio</em> calculations with the GGA + U approach revealed that spin polarization (<em>P</em>) increased with an increase in Cr and eventually reached 100 % for the alloys with <em>x</em> = 0.5. Though Fe-Co disorder affects <em>P</em>, it is still high (&gt;98 %) for alloys with <em>x</em> ≥ 0.5. Despite the smaller bandgap (0.61 eV) of Fe_1.5Cr_0.5CoSi than FeCrCoSi (0.91 eV), it has higher <em>M</em>_s, elevated <em>T</em>_C, and 100 % <em>P</em>. These factors, coupled with the challenges associated with obtaining phase pure FeCrCoSi alloy, make Fe_1.5Cr_0.5CoSi a preferred candidate for spintronic device applications.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"612 ","pages":"Article 172648"},"PeriodicalIF":2.5,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660799","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":"Statistical modeling of soft magnetic composites’ permeability","authors":"Frédéric Mazaleyrat","doi":"10.1016/j.jmmm.2024.172646","DOIUrl":"10.1016/j.jmmm.2024.172646","url":null,"abstract":"<div><div>Soft magnetic composites (SMC) also known as powder cores are widely used in many applications because of their linearity, controllable permeability and isotropy. Because of the distributed air gap, the permeability is governed by the inner demagnetizing fields. To model the permeability dependence on the filling fraction, essentially two approaches are used both based on spatial periodicity hypothesis: the non magnetic grain boundary model and the effective medium theory. Actually, the first one works only for dense materials and the second works at low concentration. Both need fitting of two parameters, the inner demagnetizing factor and the particle susceptibility, just because the periodicity hypothesis is never verified for magnetic filling factors larger than 20%. A breakaway model is proposed based on the computation of mathematical esperance of the statistical distribution of magnetic chains and the subsequent determination of demagnetizing coefficient of an ellipsoid of equivalent aspect ratio. The model is collated with permeability data from the literature for spherical or non-spherical particles based SMCs and shows a excellent agreement with only one or even without fitting parameter in the whole concentration range.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"612 ","pages":"Article 172646"},"PeriodicalIF":2.5,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660801","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":"Magnetization mechanisms for non-destructive evaluation of low-carbon steels subject to early-stage low-temperature thermal oxidation","authors":"Anita Mongshi ,&nbsp;Yves Armand Tene Deffo ,&nbsp;Nicolas Mary ,&nbsp;Pierre Tsafack ,&nbsp;Jean-François Mogniotte ,&nbsp;Benjamin Ducharne","doi":"10.1016/j.jmmm.2024.172643","DOIUrl":"10.1016/j.jmmm.2024.172643","url":null,"abstract":"<div><div>In this work, an investigation is done to identify the magnetic non-destructive testing techniques and their related magnetization mechanisms and, eventually, the associated indicators that present the most distinguishable response to changes in steel properties due to the onset and evolution of starting corrosion by thermal oxidation at low temperatures. This is found by measuring magnetic responses of Magnetic Hysteresis Cycle (MHC), Magnetic Barkhausen Noise (MBN), and Magnetic Incremental Permeability (MIP) at the early stage of corrosion. Herein, the magnetization mechanism identified by the Domain Wall Bulging (DWB) effect and represented by the indicator Δ|Z|_MIP from the MIP response is ranked the most sensitive indicator by Pearson’s linear correlation coefficient (LCC). It is immediately followed by the Domain Wall’s Irreversible Motions (DWIM) represented by the MBN coercivity indicator. Both mechanisms are associated with the structure and kinetic of the magnetic domains, respectively, under low and medium magnetic excitations. The low-temperature thermal oxidation process set out the constructive effect of the oxide layer in the strain relief effect on the overall magnetic response of the corroded specimen. Discussions and conclusions are provided, as well as perspectives regarding the applicability of magnetic non-destructive testing techniques.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"612 ","pages":"Article 172643"},"PeriodicalIF":2.5,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660795","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":"Control of spin wave demultiplexing using spin current","authors":"M.A. Morozova ,&nbsp;N.D. Lobanov ,&nbsp;O.V. Matveev ,&nbsp;S.A. Nikitov","doi":"10.1016/j.jmmm.2024.172642","DOIUrl":"10.1016/j.jmmm.2024.172642","url":null,"abstract":"<div><div>The paper reports on the principle of signals demultiplexing in the structure ferromagnetic film/normal metal/magnonic crystal. It is discovered that in such a structure there is a formation of four band gaps — spin wave forbidden bands. It is shown that depending on the frequency, the signal comes out through different ports of the structure (ferromagnetic film or magnonic crystal), i.e. there is frequency division of channels. The influence of spin current on the signal coupling at frequencies inside the band gap significantly prevails over the effect of spin current at frequencies outside the band gap. The spin current allows effective control of the main line insertion loss of a directional coupler based on such a structure. The spin current has little effect on coupling factor and isolation.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"612 ","pages":"Article 172642"},"PeriodicalIF":2.5,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660798","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":"Electronic and magnetic properties of cobalt clusters on pristine and divacancy graphene","authors":"X.-Y. Cui ,&nbsp;Khanh Nam Vu ,&nbsp;S.P. Ringer ,&nbsp;Bernard Delley ,&nbsp;C. Stampfl","doi":"10.1016/j.jmmm.2024.172633","DOIUrl":"10.1016/j.jmmm.2024.172633","url":null,"abstract":"<div><div>Using <em>ab initio</em> calculations we investigate the adsorption of Co atoms, dimers and small cobalt clusters of 5 and 13 atoms on pristine graphene and graphene with a double vacancy. We report the atomic, electronic, magnetic and energetic properties of these systems. Stable adsorption configurations tend to maximise the number of cobalt-carbon bonds. On graphene, the adsorption energy of the clusters is only about 0.4 to 1 eV, and the clusters are relatively mobile on graphene. Interestingly, for different adsorbed Co₁₃ isomers on graphene it is found that they converge to the same atomic structure. On graphene with a divacancy, the Co clusters bind in the divacancy site and isomerisation also occurs for the Co<span><math><msub><mrow></mrow><mrow><mn>5</mn></mrow></msub></math></span> cluster system as well as for Co₁₃. Co atoms and clusters can be effectively immobilised on the divacancy with corresponding adsorption energy being significantly enhanced by about 5 to 7 eV. All clusters act as electron donors in the interaction with the graphene/divacancy systems, and the amount of electron charge transfer increases with cluster size. Finite magnetic moments occur for all systems, where upon adsorption, the magnetic moment of the isolated Co atom (3<span><math><msub><mrow><mi>μ</mi></mrow><mrow><mi>B</mi></mrow></msub></math></span>) is significantly reduced due to electron transfer and bonding, resulting in values varying from <span><math><mo>≈</mo></math></span>0.9-2.2 <span><math><msub><mrow><mi>μ</mi></mrow><mrow><mi>B</mi></mrow></msub></math></span> per Co atom. For the pristine graphene substrate, the total induced magnetic moments on the carbon atoms are negligible, while on the divacancy system, they are of the order of 0.1-0.3 <span><math><msub><mrow><mi>μ</mi></mrow><mrow><mi>B</mi></mrow></msub></math></span>. The attractive physical properties of these hybrid systems could find applications in catalysis and materials science.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"612 ","pages":"Article 172633"},"PeriodicalIF":2.5,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Using NMR linewidth broadening for magnetic characterization of micrometer-size particles in silicone matrix","authors":"Yu Hao ,&nbsp;Janusz H. Hankiewicz ,&nbsp;Robert E. Camley ,&nbsp;Stephen E. Russek ,&nbsp;Zbigniew Celinski","doi":"10.1016/j.jmmm.2024.172644","DOIUrl":"10.1016/j.jmmm.2024.172644","url":null,"abstract":"<div><div>Standard magnetization measurements on samples of small magnetic particles may generate conflicting results. We compare the mass magnetization of MgZn ferrite particles in a compressed bulk material and in dry powder and find that at low fields the values can differ by as much as 50%. We show here that embedding the particles in a silicone matrix and measuring the NMR linewidth in combination with simulations establishes a new method to evaluate the magnetization of the particles at different fields and temperatures. The NMR results agree with the direct magnetization measurements of the powder samples and the magnetization measurements of the particles embedded in silicone. This work is motivated, in part, by studies on using small magnetic particles as MRI temperature indicators, and we compare the effectiveness of these particles for low-field and high-field MRI thermometry.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"612 ","pages":"Article 172644"},"PeriodicalIF":2.5,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660800","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}