Elevated critical temperature at BCS superconductor-band insulator interfaces

TL;DR

This paper demonstrates that interfaces between BCS superconductors and band insulators can exhibit higher critical temperatures than the superconductor-vacuum interface under specific conditions, without strengthening the pairing interaction.

Contribution

It reveals conditions under which superconductor-band insulator interfaces have elevated critical temperatures, a novel insight into interface superconductivity.

Findings

Interface critical temperature can surpass that of superconductor-vacuum interfaces.

Elevated T_c occurs without increasing pairing interaction strength.

Specific regimes where interface superconductivity is enhanced are identified.

Abstract

We consider the interface between a Bardeen-Cooper-Schrieffer superconductor and non-superconducting band insulator. We show that under certain conditions, such interfaces can have an elevated superconducting critical temperature, without increasing the strength of the pairing interaction at the interface. We identify the regimes where the interface critical temperature exceeds the critical temperature associated with a superconductor-vacuum interface.