静电环境对过渡金属二硫族化合物上石墨烯邻近自旋轨道耦合的影响
Influence of Electrostatic Environment on the Proximity Spin-Orbit Coupling in Graphene on Transition-Metal Dichalcogenides
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中文总结 AI 辅助
本研究通过紧束缚方法揭示扭转角和静电环境（电荷转移偶极子与能带对齐）显著调控石墨烯/TMD异质结中的邻近自旋轨道耦合，并解释文献中参数分散的根源。
中文摘要 AI 辅助
我们采用紧束缚方法研究了石墨烯/过渡金属二硫族化合物（TMD）异质结中邻近诱导的自旋轨道耦合（SOC）。我们提取了描述石墨烯层低能物理的有效四带模型的紧束缚参数，并将其作为扭转角、材料组成（MoS₂、MoSe₂、WS₂、WSe₂）、能带对齐和电荷转移偶极子的函数。我们研究了靠近石墨烯的硫族元素层上感应出的电荷转移偶极子的效应，该效应在紧束缚模型中通常被忽略，但在从头算计算中通过电荷再分布被纳入。此外，我们还探讨了能带对齐变化的影响。我们发现自旋谷和Rashba自旋轨道耦合能量以及所谓的Rashba相位（控制动量空间自旋纹理的方向）对扭转角和静电调谐表现出强烈的依赖性。我们的结果表明，能带对齐的变化和电荷再分布共同导致了文献中报道的自旋轨道参数的分散性。
英文摘要
We investigate the proximity-induced spin-orbit coupling (SOC) in graphene on transition-metal dichalcogenide (TMD) heterostructures using a tight-binding approach. The tight-binding parameters of an effective 4-band model describing the low-energy physics of the graphene layer are extracted as a function of twist angle, material composition (MoS${}_2$, MoSe${}_2$, WS${}_2$, WSe${}_2$), band alignment, and charge-transfer dipole. We investigate the effect of a charge-transfer dipole induced on the chalcogen layer closest to graphene, which is typically neglected in tight-binding models but included in ab initio calculations through charge redistribution. In addition, we explore the influence of variations in the band alignment. We find that the spin-valley and Rashba spin-orbit coupling energies as well as the so-called Rashba phase, governing the orientation of momentum-space spin textures, show a strong dependence on the twist angle and electrostatic tuning. Our results suggest that variations in band alignment and charge redistribution contribute to the spread of spin-orbit parameters reported in the literature.
发表机构
- University of Antwerp（安特卫普大学）
- University of York（约克大学）
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