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arXiv · 1906.02711

Defect-induced magnetism and Yu-Shiba-Rusinov states in twisted bilayer graphene

Alejandro Lopez-Bezanilla·Jose L. Lado
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Abstract

Atomic defects have a significant impact in the low-energy properties of graphene systems. By means of first-principles calculations and tight-binding models we provide evidence that chemical impurities modify both the normal and the superconducting states of twisted bilayer graphene. A single hydrogen atom attached to the bilayer surface yields a triple-point crossing, whereas self-doping and three-fold symmetry-breaking are created by a vacant site. Both types of defects lead to time-reversal symmetry-breaking and the creation of local magnetic moments. Hydrogen-induced magnetism is found to exist also at the doping levels where superconductivity appears in magic angle graphene superlattices. As a result, the coexistence of superconducting order and defect-induced magnetism yields in-gap Yu-Shiba-Rusinov excitations in magic angle twisted bilayer graphene.

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Alejandro Lopez-Bezanilla, Jose L. Lado. 2019-06-06. Defect-induced magnetism and Yu-Shiba-Rusinov states in twisted bilayer graphene. https://doi.org/10.1103/physrevmaterials.3.084003

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