Xu Junqing, Takenaka Hiroyuki, Habib Adela, Sundararaman Ravishankar, Ping Yuan
Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States.
Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, New York 12180, United States.
Nano Lett. 2021 Nov 24;21(22):9594-9600. doi: 10.1021/acs.nanolett.1c03345. Epub 2021 Nov 12.
Through first-principles real-time density-matrix (FPDM) dynamics simulations, we investigated spin relaxation due to electron-phonon and electron-impurity scatterings with spin-orbit coupling (SOC) in two-dimensional Dirac materials silicene and germanene at finite temperatures. We discussed the applicability of conventional descriptions of spin relaxation mechanisms by Elliott-Yafet (EY) and D'yakonov-Perel' (DP) compared to the FPDM method, which is determined by a complex interplay of intrinsic SOC, external fields, and scattering strength. For example, the electric field dependence of the spin lifetime by FPDM is close to the DP mechanism for silicene at room temperature but similar to the EY mechanism for germanene. Because of its stronger SOC strength and buckled structure in contrast to graphene, germanene has a giant spin lifetime anisotropy and spin-valley locking effect under nonzero and low temperatures. More importantly, germanene has a long spin lifetime (∼100 ns at 50 K) and an ultrahigh carrier mobility, making it advantageous for spin-valleytronic applications.
通过第一性原理实时密度矩阵（FPDM）动力学模拟，我们研究了在有限温度下二维狄拉克材料硅烯和锗烯中，由于电子 - 声子和电子 - 杂质散射以及自旋轨道耦合（SOC）导致的自旋弛豫。我们讨论了与FPDM方法相比，由Elliott - Yafet（EY）和D'yakonov - Perel'（DP）给出的自旋弛豫机制传统描述的适用性，这由本征SOC、外场和散射强度的复杂相互作用决定。例如，FPDM给出的自旋寿命对电场的依赖性在室温下对于硅烯接近DP机制，但对于锗烯则类似于EY机制。与石墨烯相比，由于锗烯具有更强的SOC强度和翘曲结构，在非零低温下具有巨大的自旋寿命各向异性和自旋 - 谷锁定效应。更重要的是，锗烯具有长的自旋寿命（在50 K时约为100 ns）和超高的载流子迁移率，这使其在自旋 - 谷电子学应用中具有优势。
