Long-range Pairing in Monolayer NbSe2 Facilitates the Emergence of Topological Superconducting States

Abstract

Abstract NbSe2, which simultaneously exhibits superconductivity and spin-orbit coupling, is anticipated to pave the way for topological superconductivity and unconventional electron pairing. In this paper, we systematically study topological superconducting (TSC) phases in monolayer NbSe2 through mixing on-site s-wave pairing (ps) with long-range pairing (psA1) based on a tight-binding model. We observe rich phases with both fixed and sensitive Chern numbers (CNs) depending on the chemical potential (μ) and out-of-plane magnetic field (Vz). As psA1 increases, the TSC phase manifests matching and mismatching features according to whether there is a bulk-boundary correspondence (BBC). Strikingly, the introduction of long-range pairing significantly reduces the critical Vz to form TSC phases compared with the pure s-wave paring. Moreover, the TSC phase can be modulated even at Vz=0 under appropriate μ and psA1, which is identified by the robust topological edge states (TESs) of ribbons. Additionally, the long-range pairing influences the hybridization of bulk and edge states, resulting in a matching/mismatching BBC with localized/oscillating TESs on the ribbon. Our finding is helpful for realization of TSC states in experiment, as well as designing and regulating TSC materials.