Effective spin dephasing mechanism in confined two-dimensional topological insulators

• Published in: Science China. Physics, mechanics & astronomy Vol. 59; no. 7; pp. 70 - 75
• Main Authors: Qi, JunJie, Liu, HaiWen, Jiang, Hua, Xie, XinCheng
• Format: Journal Article
• Language: English
• Published: Beijing Science China Press 01.07.2016; Springer Nature B.V
• Subjects: Astronomy; Backscattering; Classical and Continuum Physics; Electron phonon interactions; Electron spin; Hamiltonian functions; Observations and Techniques; Physics; Physics and Astronomy; Quantum dots; Quantum Hall effect; Robustness; Spin-orbit interactions; Topological insulators; 二维; 拓扑; 时间反演对称性; 机制; 电子-声子相互作用; 绝缘体; 退相干; 量子自旋; bound helical states; quantum spin Hall effect; spin dephasing; Rashba spin-orbit coupling; electron-phonon interaction
• ISSN: 1674-7348; 1869-1927
• DOI: 10.1007/s11433-016-0100-1

A Kramers pair of helical edge states in quantum spin Hall effect （QSHE） is robust against normal dephasing but not robust to spin dephasing. In our work, we provide an effective spin dephasing mechanism in the puddles of two-dimensional （2D） QSHE, which is simulated as quantum dots modeled by 2D massive Dirac Hamiltouian. We demonstrate that the spin dephasing effect can originate from the combination of the Rashba spin-orbit coupling and electron-phonon interaction, which gives rise to inelastic backscattering in edge states within the topological insulator quantum dots, although the time-reversal symmetry is preserved throughout. Finally, we discuss the tunneling between extended helical edge states and local edge states in the QSH quantum dots, which leads to backscattering in the extended edge states. These results can explain the more robust edge transport in InAs/GaSb QSH systems.