Origin of Subgap States in Normal-Insulator-Superconductor van der Waals Heterostructures.

ABSTRACT: Superconductivity in van der Waals materials, such as NbSe₂ and TaS₂, is fundamentally novel due to the effects of dimensionality, crystal symmetries, and strong spin-orbit coupling. In this work, we perform tunnel spectroscopy on NbSe₂ by utilizing MoS₂ or hexagonal boron nitride (hBN) as a tunnel barrier. We observe subgap excitations and probe their origin by studying various heterostructure designs. We show that the edge of NbSe₂ hosts many defect states, which strongly couple to the superconductor and form Andreev bound states. Furthermore, by isolating the NbSe₂ edge we show that the subgap states are ubiquitous in MoS₂ tunnel barriers but absent in hBN tunnel barriers, suggesting defects in MoS₂

SUBMITTER: Karnatak P 

PROVIDER: S-EPMC10103330 | biostudies-literature | 2023 Apr

REPOSITORIES: biostudies-literature