Abstract
Coupling a normal-metal wire to a superconductor induces an excitation gap in the normal metal. In the absence of disorder, the induced excitation gap is strongly suppressed by finite-size effects if the thickness of the superconductor is much smaller than the thickness of the normal metal and the superconducting coherence length . We show that the presence of disorder, either in the bulk or at the exposed surface of the superconductor, significantly enhances the magnitude of , such that approaches the superconducting gap in the limit of strong disorder. We also discuss the shift of energy bands inside the normal-metal wire as a result of the coupling to the superconducting shell.
1 More- Received 25 February 2019
- Revised 6 July 2019
DOI:https://doi.org/10.1103/PhysRevB.100.035426
©2019 American Physical Society