Spectroscopy of bulk and few-layer superconducting NbSe2 with van der Waals tunnel junctions

Ideal tunnel junctions require high-quality, defect-free insulating barriers. Here, the authors demonstrate that van der Waals tunnel barriers atop bulk and ultrathin superconducting NbSe2 sustain a stable tunneling current and allow mapping of the spectral evolution of layered superconductors.