A comparative study for spin-valley splitting of a series of van der Waals (vdW) heterostructures constructed by transition metal dichalcogenides (TMDCs) and magnetic materials has been performed by first principles calculations. It is found that the magnitude of spin-valley splitting is positively correlated the size of magnetic proximity effect closely related to Coulomb interaction, which increases with the increase of interlayer charge transfer. As a result, only when monolayer TMDCs and magnetic materials combined into type-III rather than type-I and type-II band alignment heterostructures, a large spin-valley splitting can be obtained. We demonstrated this criterion in TMDCs/NiY2 (Y=Cl, Br) vdW heterostructures by schematics of level coupling in detail, and then predicted dozens of vdW heterostructures with possible large spin-valley splitting. This discovery can help to quickly determine whether the material can achieve a large spin-valley splitting, and the predicted materials will provide good guidance for the experimentalists.

中文翻译：

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III型能带对准的范德华异质结构中的大谷裂

通过第一原理计算，对由过渡金属二卤化物（TMDC）和磁性材料构成的一系列范德华（vdW）异质结构的自旋谷分裂进行了比较研究。发现自旋谷分裂的大小与与库仑相互作用密切相关的磁邻近效应的大小呈正相关，其随层间电荷转移的增加而增加。结果，仅当单层TMDC和磁性材料结合成III型而不是I型和II型能带取向异质结构时，才能获得大的自旋谷分裂。通过详细的能级耦合原理，我们在TMDCs / NiY2（Y = Cl，Br）vdW异质结构中证明了这一标准，然后预测了数十个可能具有大自旋谷分裂的vdW异质结构。这一发现可以帮助快速确定材料是否可以实现大的自旋谷分裂，并且预测的材料将为实验者提供良好的指导。