Electronic structure and spin polarization of Mn-containing dilute magnetic III-V semiconductors
Electronic structure and spin polarization of Mn-containing dilute magnetic III-V semiconductors
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DOI：
10.1103/physrevb.64.245205
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发表时间：
2001
影响因子：
3.7
通讯作者：
Manish Jain;L. Kronik;J. Chelikowsky;V. Godlevsky
中科院分区：
文献类型：
--
作者：
Manish Jain;L. Kronik;J. Chelikowsky;V. Godlevsky
我们提出了稀磁半导体 ${\mathrm{Mn}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ 电子结构的从头算密度泛函计算，以及 ${\mathrm{Mn}}_{x}{\mathrm{In}}_{1\ensuremath{-}x}\mathrm{As}$ 与现实的 $x=0.063.$ 我们发现 Mn 的引入扰乱了最近的 As 原子的位置，但没有破坏四面体对称性。这两种材料都没有被发现是严格的半金属。然而，在这两种材料中，Mn 含量都会导致多数自旋价带最大值比少数自旋价带最大值高 $\ensuremath{\sim}0.5$ eV。这种大的价带分裂主要是由于 As $4p$ 和 Mn $3d$ 轨道的杂化。它会产生一个显着的能量范围，其中空穴具有明确的自旋。发现该范围内的空穴的有效质量与 GaAs 和 InAs 的有效质量相当。因此，在理想的、无序的情况下，自旋极化输运可以通过简单能带图背景下的常规输运来解释。这导致了这些材料 100% 自旋注入的理论极限。在足够有序的材料中达到这一极限还需要对费米能级位置进行仔细的“工程”和足够低的温度。
We present ab initio density-functional calculations for the electronic structure of the dilute magnetic semiconductors ${\mathrm{Mn}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ and ${\mathrm{Mn}}_{x}{\mathrm{In}}_{1\ensuremath{-}x}\mathrm{As}$ with a realistic $x=0.063.$ We find that the introduction of Mn perturbs the position of the nearest As atoms, but does not break the tetrahedral symmetry. Neither material is found to be strictly half metallic. However, in both materials the Mn content results in a majority-spin valence-band maximum that is $\ensuremath{\sim}0.5$ eV above the minority-spin valence-band maximum. This large valence-band split is primarily due to the hybridization of As $4p$ and Mn $3d$ orbitals. It results in a significant energy range where holes have a well-defined spin. The effective masses of holes in this range are found to be comparable to those of GaAs and InAs. Hence, in an ideal, disorder-free situation, spin-polarized transport may be explained by conventional transport in the context of a simple band picture. This leads to a theoretical limit of 100% spin injection from these materials. Attaining this limit in a sufficiently ordered material also requires a careful ``engineering'' of the Fermi-level position and a sufficiently low temperature.