Saha Srijan Kumar, Liu Zhen, Dutta Gargi
0103, Khaihata, Malda, 732142, West Bengal, India.
Department of Physics, Beijing Normal University, Beijing, 100875, China.
Sci Rep. 2017 Oct 16;7(1):13221. doi: 10.1038/s41598-017-13276-5.
Traditional density functional theory (DFT) miserably fails to reproduce the experimental volume and magnetic anisotropy of D0 MnGa, which has recently become one of the most sought-after materials in order to achieve a stable spin switching at low current density. Despite great progress over the last 10 years, this issue has hitherto remained unsolved. Here, taking into account the effects of strong electronic correlations beyond what is included in standard DFT, we show by comparison with the experiment that the DFT+U method is capable of quantitatively describing the volume and the magnetic anisotropy energy (MAE) in this alloy with physically meaningful choice of onsite Coulomb-U parameter. For the first time using a plane-wave code, we decompose MAE into spin channel-resolved components in order to determine spin-flip and spin-conserving contributions. The Mn atom at the tetrahedral site is identified as the primary source of the high perpendicular MAE with the most dominant spin-orbit coupling (SOC) occurring between its two orbital pairs: ↑↑ coupling and ↓↓ coupling between [Formula: see text] and d , and ↑↓ coupling between d and [Formula: see text]. Using the SOC-perturbation theory model, we provide interpretation of our numerical results. These results are important for quantitative microscopic understanding of the large perpendicular MAE observed in this material, and should assist in harnessing its potential for applications in futuristic spintronic devices.
传统密度泛函理论（DFT）在再现D0 MnGa的实验体积和磁各向异性方面遭遇惨败，D0 MnGa最近已成为最受追捧的材料之一，旨在实现低电流密度下稳定的自旋切换。尽管在过去十年取得了巨大进展，但这个问题迄今仍未解决。在此，考虑到超出标准DFT所包含的强电子关联效应，我们通过与实验对比表明，DFT + U方法能够在对在位库仑U参数进行物理上有意义的选择时，定量描述该合金的体积和磁各向异性能量（MAE）。我们首次使用平面波代码，将MAE分解为自旋通道分辨的分量，以确定自旋翻转和自旋守恒的贡献。四面体位置的Mn原子被确定为高垂直MAE的主要来源，其两个轨道对之间存在最主要的自旋轨道耦合（SOC）：[公式：见原文]和d之间的↑↑耦合和↓↓耦合，以及d和[公式：见原文]之间的↑↓耦合。使用SOC微扰理论模型，我们对数值结果进行了解释。这些结果对于定量微观理解该材料中观察到的大垂直MAE很重要，并应有助于挖掘其在未来自旋电子器件中的应用潜力。
