Te is a naturally $p$-doped semiconductor with a chiral structure, where an electrical current causes the conduction electrons to become spin-polarized parallel to the transport direction. In this paper, we present a comprehensive theoretical study of this effect, named current-induced spin polarization (CISP), by employing density functional theory (DFT) combined with the nonequilibrium Green's function (NEGF) technique for quantum transport. CISP can be quantitatively described in terms of the nonequilibrium spin density, which we show to be localized around the atoms. We then compute the atomic magnetic moments as a function of doping and electronic temperature, obtaining results overall consistent with those of previous theoretical studies. Beyond that, our DFT + NEGF calculations show that CISP also leads to a spin current, which is found to be quite a large fraction of the charge current, indicating that Te can be an efficient material for spin transport. We further predict that the resistance along a ballistic Te wire changes when an external magnetic field is applied parallel or antiparallel to the direction of the charge current. The computed magnetoresistance ratio is, however, quite small ($\sim 0.025\%$). Finally, we conclude by arguing that CISP, as treated within the DFT + NEGF framework, coincides with the phenomenon called chiral-induced spin selectivity, recently reported in several nanojunctions.

中文翻译：

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手性碲中电流诱导的自旋极化：第一原理量子输运研究

Te 是一个自然$p$具有手性结构的掺杂半导体，其中电流导致传导电子变得平行于传输方向的自旋极化。在本文中，我们通过采用密度泛函理论（DFT）与非平衡格林函数（NEGF）技术相结合的量子传输技术，对这种效应进行了全面的理论研究，称为电流诱导自旋极化（CISP）。 CISP 可以用非平衡自旋密度来定量描述，我们证明非平衡自旋密度位于原子周围。然后，我们计算原子磁矩作为掺杂和电子温度的函数，获得与之前的理论研究总体一致的结果。除此之外，我们的 DFT + NEGF 计算表明，CISP 还会产生自旋电流，该电流占充电电流的很大一部分，这表明 Te 可以成为自旋传输的有效材料。我们进一步预测，当与充电电流方向平行或反平行施加外部磁场时，沿弹道 Te 线的电阻会发生变化。然而，计算出的磁阻比非常小（$～0.025\%$）。最后，我们得出的结论是，在 DFT + NEGF 框架内处理的 CISP 与最近在几个纳米结中报道的称为手性诱导自旋选择性的现象相一致。