Liang Xilong, Qin Chengbing, Gao Yan, Han Shuangping, Zhang Guofeng, Chen Ruiyun, Hu Jianyong, Xiao Liantuan, Jia Suotang
State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan, Shanxi 030006, China.
Nanoscale. 2021 May 20;13(19):8966-8975. doi: 10.1039/d1nr00019e.
Monolayer transition metal dichalcogenides, manifesting strong spin-orbit coupling combined with broken inversion symmetry, lead to coupling of spin and valley degrees of freedom. These unique features make them highly interesting for potential spintronic and valleytronic applications. However, engineering spin-orbit coupling at room temperature as demanded after device fabrication is still a great challenge for their practical applications. Here we reversibly engineer the spin-orbit coupling of monolayer MoS2 by laser irradiation under controlled gas environments, where the spin-orbit splitting has been effectively regulated within 140 meV to 200 meV. Furthermore, the photoluminescence intensity of the B exciton can be reversibly manipulated over 2 orders of magnitude. We attribute the engineering of spin-orbit splitting to the reduction of binding energy combined with band renormalization, originating from the enhanced absorption coefficient of monolayer MoS2 under inert gases and subsequently the significantly boosted carrier concentrations. Reflectance contrast spectra during the engineering stages provide unambiguous proof to support our interpretation. Our approach offers a new avenue to actively control the spin-orbit splitting in transition metal dichalcogenide materials at room temperature and paves the way for designing innovative spintronic devices.
单层过渡金属二硫属化物表现出强烈的自旋轨道耦合以及反演对称性破缺，从而导致自旋和能谷自由度的耦合。这些独特特性使其在潜在的自旋电子学和能谷电子学应用方面极具吸引力。然而，在器件制造后按要求在室温下调控自旋轨道耦合对于其实际应用而言仍是巨大挑战。在此，我们在可控气体环境下通过激光辐照可逆地调控单层二硫化钼的自旋轨道耦合，其中自旋轨道分裂已在140毫电子伏特至200毫电子伏特范围内得到有效调节。此外，B激子的光致发光强度可在超过两个数量级的范围内可逆地操控。我们将自旋轨道分裂的调控归因于结合能的降低以及能带重整化，这源于单层二硫化钼在惰性气体下吸收系数的增强以及随后显著提高的载流子浓度。调控阶段的反射率对比光谱为支持我们的解释提供了明确证据。我们的方法为在室温下主动控制过渡金属二硫属化物材料中的自旋轨道分裂提供了一条新途径，并为设计创新型自旋电子器件铺平了道路。
