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arXiv 2402.09045cond-mat.mes-hall
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扭曲石墨烯/SnTe异质结中巨大的非对称近邻诱导自旋轨道耦合

Giant asymmetric proximity-induced spin-orbit coupling in twisted graphene/SnTe heterostructure

Marko Milivojević, Martin Gmitra, Marcin Kurpas, Ivan Štich, Jaroslav Fabian

AI总结:

本文分析了石墨烯与铁电SnTe构成的三度扭曲异质结,发现通过近邻效应可实现大于20 meV的巨大非对称自旋劈裂,铁电诱导的Rashba耦合占主导,证明IV族单硫族化合物是诱导强自旋轨道耦合的可行替代方案。

摘要:

我们分析了由石墨烯和面内铁电SnTe组成的三度扭曲双层异质结中的自旋轨道耦合效应,目标是通过近邻效应将自旋轨道耦合从SnTe转移到石墨烯。结果表明,由于扭曲单层的不兼容互对称性引起的点对称性破缺以及强杂化,对靠近狄拉克点的石墨烯自旋劈裂产生巨大影响,自旋劈裂值大于20 meV。靠近狄拉克点的石墨烯能带结构和自旋期望值可以用无对称性模型描述,这引发了相对于三重对称石墨烯/过渡金属硫族化合物异质结的不同类型相互作用。我们表明,狄拉克锥右移载流子与SnTe能带的强杂化在动量空间中引起巨大的非对称自旋劈裂。此外,我们发现石墨烯中铁电诱导的Rashba自旋轨道耦合是对总Rashba场的主导贡献,其有效面内电场几乎与SnTe单层的(面内)铁电极化方向对齐。我们还预测了面内自旋弛豫率的各向异性。结果表明,IV族单硫族化合物MX(M=Sn, Ge;X=S, Se, Te)是替代过渡金属硫族化合物在石墨烯中诱导强自旋轨道耦合的可行方案。

英文摘要:

We analyze the spin-orbit coupling effects in a three-degree twisted bilayer heterostructure made of graphene and an in-plane ferroelectric SnTe, with the goal of transferring the spin-orbit coupling from SnTe to graphene, via the proximity effect. Our results indicate that the point-symmetry breaking due to the incompatible mutual symmetry of the twisted monolayers and a strong hybridization has a massive impact on the spin splitting in graphene close to the Dirac point, with the spin splitting values greater than 20 meV. The band structure and spin expectation values of graphene close to the Dirac point can be described using a symmetry-free model, triggering different types of interaction with respect to the threefold symmetric graphene/transition-metal dichalcogenide heterostructure. We show that the strong hybridization of the Dirac cone's right movers with the SnTe band gives rise to a large asymmetric spin splitting in the momentum space. Furthermore, we discover that the ferroelectricity-induced Rashba spin-orbit coupling in graphene is the dominant contribution to the overall Rashba field, with the effective in-plane electric field that is almost aligned with the (in-plane) ferroelectricity direction of the SnTe monolayer. We also predict an anisotropy of the in-plane spin relaxation rates. Our results demonstrate that the group-IV monochalcogenides MX (M=Sn, Ge; X=S, Se, Te) are a viable alternative to transition-metal dichalcogenides for inducing strong spin-orbit coupling in graphene.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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