Prediction of half-metallic gap formation and Fermi level position in Co-based Heusler alloy epitaxial thin films through anisotropic magnetoresistance effect
Prediction of half-metallic gap formation and Fermi level position in Co-based Heusler alloy epitaxial thin films through anisotropic magnetoresistance effect
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DOI：
10.1103/physrevmaterials.6.064411
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发表时间：
2022-06
影响因子：
3.4
通讯作者：
V. Kushwaha;S. Kokado;S. Kasai;Y. Miura;T. Nakatani;R. Kumara;H. Tajiri;T. Furubayashi;K. Hono;Y. Sakuraba
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文献类型：
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作者：
V. Kushwaha;S. Kokado;S. Kasai;Y. Miura;T. Nakatani;R. Kumara;H. Tajiri;T. Furubayashi;K. Hono;Y. Sakuraba
我们研究了具有不同组成和原子序数的(CFGG)外延薄膜的各向异性磁阻(AMR)效应与温度的关系，并基于建立的理论模型考察了AMR与半金属电子结构的关系。在具有标准组成和高原子序度的CFGG薄膜中，在10K下归一化的AMR的电阻变化(Δρ)的依赖性是最小的。相反，由于富Co组分而具有较大的原子无序性的薄膜表现出较大的Δρ和。我们的磁阻理论模型很好地解释了这一行为，即费米能级在半金属禁带中心附近的半金属铁磁体由于没有/很少的局域态而对Δρ表现出很小的依赖性。相反，由于涉及态的热激发-散射的贡献，对于接近带隙边缘或大带隙内态的半金属材料，Δρ将发生较大的变化。此外，我们还研究了各种半金属钴基Heusler合金薄膜的Δρ随时间的变化，发现这一行为与我们的理论预测一致。本研究证明，根据磁阻效应对Δρ的依赖关系，可以很容易地预测半金属材料中半金属带隙的形成和位置，这可能是有效筛选半金属材料的一种简便方法。
We have investigated the temperaturedependence of the anisotropic magnetoresistance (AMR) effect of(CFGG) epitaxial thin films having different compositions and atomic orders to examine the relation between AMR and the half-metallic electronic structure based on a developed theoretical model. Thedependence of the resistance change (Δρ) of the AMR normalized at 10Kis minimal in the CFGG films having a standard composition and high atomic order. In contrast, the films having a large atomic disorder due to the Co-rich composition exhibit a large reduction of Δρ with. Our theoretical model of AMR well explains this behavior; namely, the half-metallic ferromagnets having the Fermi levelaround the center of the half-metallic gap are predicted to show a smalldependence of Δρ because of no/few localizedstates at. On the contrary, a large change of Δρwithis expected for the half-metallic materials havingclose to gap edges or large in-gap states because of the contribution of thermally exciteds-dscattering involving thestates. Moreover, we have also investigated the variation of Δρwithfor the thin films of various half-metallic Co-based Heusler alloys and found the behavior that agrees with our theoretical prediction. The present study proves that the formation of a half-metallic gap and the position ofin a half-metallic material are readily predictable from thedependence of Δρ of the AMR effect, which can be a facile way for efficient screening of half-metallic materials.