Twisted Bogoliubov quasiparticles in the superconducting NbSe$_2$ monolayer on graphene

TL;DR

This study uses spectroscopic-imaging STM to explore how twisting NbSe2 monolayers on graphene affects electronic states and superconductivity, revealing twisted Bogoliubov quasiparticle interference patterns linked to Fermi surface overlap.

Contribution

It demonstrates the impact of twist angle on quasiparticle interference patterns and superconductivity in NbSe2/graphene heterostructures, providing insights into twist-controlled electronic properties.

Findings

Twisted interference patterns originate from specific momentum space regions.

Fermi surface overlap is sensitive to the twist angle.

Twist angle can be used to tune superconductivity.

Abstract

The superconducting properties of layered materials can be controlled by thinning, stacking, and twisting, demanding investigation of electronic states by spectroscopic means at the nanometer scale. Here, we reveal the spatial variations of the electronic states in heterostructures of the superconducting monolayer NbSe$_2$/graphene using spectroscopic-imaging scanning tunneling microscopy. The NbSe$_2$ monolayer grown by molecular beam epitaxy is naturally twisted with respect to the graphene substrate and exhibits interference patterns of Bogoliubov quasiparticles twisted with respect to the NbSe$_2$ and graphene lattices. We find that the twisted interference patterns originate from a sextet of regions in momentum space where the Fermi surfaces of NbSe$_2$ and graphene overlap. The Fermi surface overlap is sensitive to the twist angle, providing a knob to tune superconductivity.