报告题目：Persistent skyrmion lattice of non-interacting electrons in spin-orbit coupled quantum wells

报 告 人：付吉永 博士

时    间：2017年11月29日 14:30

地    点：物理楼313报告厅

主    办：天游线路检测中心

报告摘要：In this talk, I will mainly talk about our recent work about spin helix and skyrmion lattice.[1] Apersistent spin helix (PSH) is a robust helical spin-density pattern arising in disordered 2D electron gases with Rashba α and Dresselhaus β spin-orbit (SO) tuned couplings, i.e., α=±β. We observe the emergence of a Persistent Skyrmion Lattice (PSL) resulting from the coherent superposition of PSHs along orthogonal directions -- crossed PSHs -- in wells with two occupied subbands ν=1,2. For realistic GaAs wells we show that the Rashba αν and Dresselhaus βν couplings can be simultaneously tuned to equal strengths but opposite signs, e.g., α1=-β1 and α2=β2. In this regime and away from band anticrossings, our non-interacting electron gas sustains a topologically non-trivial skyrmion-lattice spin-density excitation, which inherits the robustness against spin-independent disorder and interactions from its underlying crossed PSHs. We find that the spin relaxation rate due to the interband SO coupling is comparable to that of the cubic Dresselhaus term as a mechanism of the PSL decay. Near anticrossings, the interband-induced spin mixing leads to unusual spin textures along the energy contours beyond those of the Rahsba-Dresselhaus bands. Our PSL opens up the unique possibility of observing topological phenomena, e.g., topological and skyrmion Hall effects, in ordinary GaAs wells with non-interacting electrons. Finally, I may also briefly introduce our recent work in other subjects, e.g. 2D transition metal dichalcogenides.[2]