Abstract
We study the two-dimensional superconductor-insulator transition (SIT) in thin films of tantalum nitride. At zero magnetic field, films can be disorder-tuned across the SIT by adjusting thickness and film stoichiometry; insulating films exhibit classical hopping transport. Superconducting films exhibit a magnetic-field-tuned SIT, whose insulating ground state at high field appears to be a quantum-corrected metal. Scaling behavior at the field-tuned SIT shows classical percolation critical exponents , with a corresponding critical field , the upper critical field. The Hall effect exhibits a crossing point near , but with a nonuniversal critical value comparable to the normal-state Hall resistivity. We propose that high-carrier-density metals will always exhibit this pattern of behavior at the boundary between superconducting and (trivially) insulating ground states.
- Received 29 May 2017
- Revised 10 October 2017
DOI:https://doi.org/10.1103/PhysRevB.96.134522
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