Abstract
We report on fabrication of devices integrating with other van der Waals materials, measuring transport properties as well as tunneling spectra at variable magnetic fields and temperatures down to 35 mK. Transport measurements are reliable and repeatable, revealing temperature and magnetic field dependence in agreement with prior results, confirming that fabrication processing does not alter bulk properties. However, cross-sectional scanning transmission microscopy reveals oxidation of the surface, which may explain a lower yield of tunneling device fabrication. We nonetheless observe hard-gap planar tunneling into through a barrier. Notably, a minimal hard gap of 0.5 meV persists up to a magnetic field of 9 T in the plane and 3 T out of plane. This may be the result of very small junction dimensions or a quantum-limit minimal energy spacing between vortex bound states. We also observe defect-assisted tunneling, exhibiting bias-symmetric resonant states, which may arise due to resonant Andreev processes.
- Received 29 May 2019
- Revised 28 July 2019
DOI:https://doi.org/10.1103/PhysRevB.100.064517
©2019 American Physical Society