论文标题
量子旋转空间相的自旋电流密度功能理论
Spin Current Density Functional Theory of the Quantum Spin-Hall Phase
论文作者
论文摘要
自旋电流密度功能理论（SCDFT）是标准DFT的概括，以处理由自旋轨道耦合相互作用产生的有效外部场中的费米子系统。即使在没有自旋两极化的情况下，SCDFT也需要电子电子潜力来依赖自旋电流$ \ mathbf {j}^x $，$ \ Mathbf {j}^y $和$ \ Mathbf {J}^Z $，而最近才成为实践中的重视量子量化量子模拟的实用性模拟[J}^Z $。修订版B {\ bf 102}，235118（2020）]。在这里，我们将SCDFT应用于量子旋转阶段，并显示其相对于DFT的电子结构的描述（甚至定性）如何改进。我们研究BI（001）2D双层及其带绝缘子到拓扑绝缘体相变（通过$ s +p_z \ leftrightArrow p_x +ip_y $ band倒置）作为机械应变的函数。我们表明，SCDFT的电子电子电势中自旋电流的明确说明是在拓扑相变的开始时在价带结构中$γ$点出现的狄拉克锥的关键。最后，使用简单的一阶$ \ mathbf {k} \ cdot \ mathbf {p} $ quasi-depegenate扰动理论模型使用简单的一阶$ \ mathbf {k} \ cdot \ mathbf {k} \ cdot \ mathbf {k} \ cdot \ mathbf {k} \ cdot \ mathbf {k} \ cdot \ mathbf {k} \ cdot \ mathbf {k} \ cdot \ mathbf {k} \ cdot \ mathbf {
The spin current density functional theory (SCDFT) is the generalization of the standard DFT to treat a fermionic system embedded in the effective external field produced by the spin-orbit coupling interaction. Even in the absence of a spin polarization, the SCDFT requires the electron-electron potential to depend on the spin currents $\mathbf{J}^x$, $\mathbf{J}^y$ and $\mathbf{J}^z$, which only recently was made possible for practical relativistic quantum-mechanical simulations [Phys. Rev. B {\bf 102}, 235118 (2020)]. Here, we apply the SCDFT to the quantum spin-Hall phase and show how it improves (even qualitatively) the description of its electronic structure relative to the DFT. We study the Bi (001) 2D bilayer and its band insulator to topological insulator phase transition (via $s+p_z \leftrightarrow p_x +ip_y$ band inversion) as a function of mechanical strain. We show that the explicit account of spin currents in the electron-electron potential of the SCDFT is key to the appearance of a Dirac cone at the $Γ$ point in the valence band structure at the onset of the topological phase transition. Finally, the valence band structure of this system is rationalized using a simple first-order $\mathbf{k} \cdot \mathbf{p}$ quasi-degenerate perturbation theory model.
