Multiple-gap structure in electric-field-induced surface superconductivity

TL;DR

This study investigates the unique multiple-gap structure in electric-field-induced surface superconductivity, revealing in-gap states and depth-dependent properties through Bogoliubov-de Gennes analysis in SrTiO3.

Contribution

It introduces a detailed analysis of the sub-band dependent gap structure in surface superconductivity, highlighting effects of screening and confinement potentials.

Findings

Presence of in-gap states even with isotropic s-wave pairing

Depth-dependent variation of local superconductivity

Multiple-gap structure due to sub-band effects

Abstract

Local superconducting gap structure is studied as a function of nanoscale depth in electric-field-induced surface superconductivity such as in SrTiO3. We examine solutions of Bogoliubov-de Gennes equation in two limiting confinement potential cases of electric field with and without screening effects. As unique properties different from bulk superconductivity, there appear in-gap states even for isotropic s-wave pairing, due to multiple gap structure of sub-band dependent surface superconductivity. These determine the depth-dependence of local superconductivity.