Quantized Spin Transport in Magnetically-D isordered Quantum Spin Hall Systems
Quantized Spin Transport in Magnetically-D isordered Quantum Spin Hall Systems
复制标题
磁D无序量子自旋霍尔系统中的量子化自旋输运
DOI：
10.1143/jpsj.80.124712
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发表时间：
2011
影响因子：
1.7
通讯作者：
Kiminori Hattori
中科院分区：
文献类型：
--
作者：
K. Sato;H. Murakami;K. Fujimoto;M. Nakata;and Y. Kobayashi;Kiminori Hattori
在量子自旋霍尔(QSH)系统中，形成了螺旋边态，它以相反的方向传输具有相反自旋的电子。这些状态本质上对时间反转不变的扰动，如非磁性无序是健壮的，但容易受到打破时间反转对称性的磁性无序的影响。在这项研究中，我们在非平衡态格林函数形式的基础上，研究了磁无序对QSH系统中电荷和自旋输运的影响。我们证明了在无限大系统中，量子化的电荷输运被任何弱磁无序破坏，而量子化和守恒的自旋输运在特定的偏置条件下幸存于磁无序中，只要体隙保持不变。这两个截然不同的特征可以用螺旋边缘通道中允许的自旋翻转后向散射及其对电荷和自旋电流的影响来解释。
Helical edge states that transport electrons with opposing spins in opposite directions are formed in a quantum spin Hall (QSH) system. These states are essentially robust against time-reversal-invariant perturbations such as nonmagnetic disorder, but are vulnerable to magnetic disorder that breaks time reversal symmetry. In this study, we explore how magnetic disorder affects charge and spin transport in the QSH system on the basis of the nonequilibrium Green's function formalism. We show that quantized charge transport is destroyed by any weak magnetic disorder in an infinitely large system, whereas quantized and conserved spin transport survives magnetic disorder under a specific bias condition as long as the bulk gap remains intact. These two contrasting features are explained in terms of the spin-flip backward scattering allowed in helical edge channels and its effects on charge and spin currents.