Observation of in-gap states in a two-dimensional CrI2/NbSe2 heterostructure

Peigen Li; Jihai Zhang; Di Zhu; Cui-Qun Chen; Enkui Yi; Bing Shen; Yusheng Hou; Zhongbo Yan; Dao-Xin Yao; Donghui Guo; Dingyong Zhong

doi:10.1021/acs.nanolett.4c01848

arXiv · 2403.06215

Observation of in-gap states in a two-dimensional CrI2/NbSe2 heterostructure

Peigen Li·Jihai Zhang·Di Zhu·Cui-Qun Chen·Enkui Yi·Bing Shen·Yusheng Hou·Zhongbo Yan·Dao-Xin Yao·Donghui Guo·Dingyong Zhong

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Abstract

Low-dimensional magnetic structures coupled with superconductors are promising platforms for realizing Majorana zero modes, which have potential applications in topological quantum computing. Here, we report a two-dimensional (2D) magnetic-superconducting heterostructure consisting of single-layer chromium diiodide (CrI2) on a niobium diselenide (NbSe2) superconductor. Single-layer CrI2 nanosheets, which hold antiferromagnetic (AFM) ground states by our first-principles calculations, were epitaxially grown on the layered NbSe2 substrate. Using scanning tunneling microscopy/spectroscopy, we observed robust in-gap states spatially located at the edge of the nanosheets and defect-induced zero-energy peaks inside the CrI2 nanosheets. Magnetic-flux vortices induced by an external field exhibit broken threefold rotational symmetry of pristine NbSe2 superconductor, implying the efficient modulation of the interfacial superconducting states by the epitaxial CrI2 layer. A phenomenological model suggests the existence of chiral edge states in a 2D AFM-superconducting hybrid system with an even Chern number, providing a qualitatively plausible understanding for our experimental observation.

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Peigen Li, Jihai Zhang, Di Zhu, Cui-Qun Chen, Enkui Yi, Bing Shen, Yusheng Hou, Zhongbo Yan, Dao-Xin Yao, Donghui Guo, Dingyong Zhong. 2024-03-10. Observation of in-gap states in a two-dimensional CrI2/NbSe2 heterostructure. https://doi.org/10.1021/acs.nanolett.4c01848

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