Uniaxial magnetic anisotropy of transition metal oxides: role of local lattice deformation
Uniaxial magnetic anisotropy of transition metal oxides: role of local lattice deformation
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DOI：
10.1088/1361-6463/ab7324
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发表时间：
2020-03
期刊：
影响因子：
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通讯作者：
J. Inoue;H. Onoda;H. Yanagihara
中科院分区：
文献类型：
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作者：
J. Inoue;H. Onoda;H. Yanagihara
用电子理论研究了磁性离子周围的局域晶格结构对过渡金属氧化物，特别是铁氧体单轴磁各向异性的影响。我们研究了M型六方铁氧体、四方变形尖晶石铁氧体和钛铁矿(CoMnO_3)。采用具有自旋-轨道相互作用的紧束缚方案(LS耦合)计算了过渡金属(TM)离子和周围氧离子组成的小团簇的电子结构和MA能量。M型铁氧体单轴MA的计算结果与用第一原理计算的结果以及实验结果相吻合，表明了本方案的有效性。高的数值精度使我们可以得出结论：Fe~(3+)和O_2~(2+)−离子之间的p-−_d混合对于M型铁氧体的单轴MA是至关重要的，而Tm离子周围局域晶格结构的改变可能会引起掺Fe~(2+)或Co~(2+)的M型铁氧体的局域单轴MA的符号变化。四角形变尖晶石型铁氧体的单轴MA结果与实验结果吻合较好。这些观察结果可能为提高铁氧体中单轴MA的大小提供了一种可行的方法。
We study the effects of the local lattice structure around magnetic ions, on the uniaxial magnetic anisotropy (MA) in transition metal oxides, particularly ferrites, using the electron theory. We address M-type hexagonal ferrites, tetragonally distorted spinel ferrites, and an ilmenite (CoMnO3). The tight-binding scheme with spin–orbit interaction (LS coupling) is applied to calculate the electronic structure and MA energy of small clusters composed of a transition metal (TM) ion and surrounding oxygen ions. The results of uniaxial MA for M-type ferrites agree with those calculated using the first principles as well as those obtained experimentally, indicating the validity of the present scheme. The high numerical accuracy enables us to conclude that the p − d mixing between Fe3+ and O2− ions is crucial for the uniaxial MA of M-type ferrites and that a change in the local lattice structure around TM ions may cause a sign change in the local uniaxial MA of Fe2+ or Co2+ doped in M-type ferrites. The results of the uniaxial MA in tetragonally distorted spinel ferrites agree well with the experimental ones. These observations may indicate a feasible method to enhance the magnitude of the uniaxial MA in ferrites.