单层二硫化钼材料中磁性杂质诱导的Yu-Shiba束缚态与近藤效应研究

Kondo effect is one of the most important quantum many body correlation effects. Recently, the Kondo effect is intensively investigated in mesoscopic systems due to the precise controllability. However, the Kondo effect in the system containing spin-orbit coupling has no consistent conclusions, and the influences of spin-orbit coupling on Kondo effect is still in controversy. The monolayer MoS2 is a direct gap semiconductor, which includes the spin-valley locking and the spin-orbit coupling originating from the Molybdenum atom. In this proposal, we would study the microscopic mechanism of the Kondo effect of magnetic impurity in monolayer MoS2 by the numerical renormalization group method, the Green’s function theory, and so on. We would clarify the influence of the spin-orbit coupling and the spin-valley locking on the Kondo screening. It is found that the monolayer MoS2 displays Ising superconductivity and nontrivial topological properties. We will study the Yu-Shiba bound state induced by the impurity in the gap of Ising superconductor, and discuss the influence of the impurity on the topological properties of monolayer MoS2. This program would deepen the understanding on the strong correlation effects in the quantum materials containing spin-orbit coupling. It would provide theoretical supports for designing new quantum devices.

近藤效应是凝聚态物理中重要的量子多体关联现象。近年来随着实验技术的发展，人们对介观量子体系中的近藤效应进行了大量可控性研究。但对于含自旋轨道耦合电子系统中磁性杂质近藤问题，人们对自旋轨道耦合如何影响近藤效应，尚无一致结论。单层二硫化钼材料是直接带隙半导体，它具有自旋-能谷锁定特性且钼原子具有强自旋轨道耦合。本项目将利用数值重整化群和多体格林函数理论等方法对单层二硫化钼中磁性杂质近藤效应进行研究，揭示自旋轨道耦合与自旋-能谷锁定对近藤屏蔽的影响及其微观物理机制。最近实验还发现单层二硫化钼具有Ising超导性和非平庸拓扑性质，超导态二硫化钼中的磁杂质问题是个非常有趣的课题。我们将研究磁性杂质在单层二硫化钼Ising超导能隙中诱导的Yu-Shiba束缚态，并讨论磁性杂质散射对体系拓扑性质的影响。本研究将有助于理解自旋轨道耦合对二维材料中多体强关联效应的影响，同时为设计新型量子器件提供理论支持。

超导与近藤效应都是凝聚态物理中重要的量子多体关联现象，本项目在介观量子体系中研究这两种多体现象之间的相互作用。本项目主要目标是单层MoS2材料Ising超导中磁性杂质的近藤效应，其涉及近藤效应与Ising超导电性相互竞争的物理。本项目首先研究了超导体系中磁性杂志近藤屏蔽的基本问题，对于超导体系中磁性杂质局域磁矩的近藤屏蔽给出微观物理图像，很好地解释相关实验结果。由于单层MoS2材料具有空间反演对称破缺，具有Rashba自旋轨道耦合作用，其超导态可能具有拓扑非平庸性质，因此本项目进一步研究了该年度研究了含有自旋轨道耦合二维超导体系的杂质近藤屏蔽效应，提出了Rashba自旋轨道耦合诱导新的近藤屏蔽通道，并给出其微观物理机制。 接下来，我们研究了单层MoS2材料中磁性杂质近藤效应与Ising超导相互作用基态相图，讨论了基态变化导致的能级交叉量子相变及其调控，为实验研究给出理论依据。在本项目支持下，申请人与国内学者合作系统研究了拓扑半金属中磁性杂质近藤效应,提出测量拓扑半金属表面态的新方案，磁性原子局域磁矩调控相关问题，得到一些具有新颖性的结果。