Specular Andreev reflection in thin films of topological insulators

TL;DR

This paper theoretically demonstrates that a gate electric field can induce and enhance perfect specular Andreev reflection in thin film topological insulator N/S junctions, with potential applications in quantum devices.

Contribution

It introduces the possibility of controlling specular Andreev reflection in topological insulator thin films via electric fields, a novel approach in the field.

Findings

Specular Andreev reflection probability increases with electric field.

Perfect Andreev reflection occurs at specific excitation energies for all incident angles.

Thermal conductance shows exponential temperature dependence.

Abstract

We theoretically reveal the possibility of specular Andreev reflection in a thin film topological insulator normal-superconductor (N/S) junction in the presence of a gate electric field. The probability of specular Andreev reflection increases with the electric field, and electron-hole conversion with unit efficiency happens in a wide experimentally accessible range of the electric field. We show that perfect specular Andreev reflection can occur for all angles of incidence with a particular excitation energy value. In addition, we find that the thermal conductance of the structure displays exponential dependence on the temperature. Our results reveal the potential of the proposed topological insulator thin-film-based N/S structure for the realization of intraband specular Andreev reflection.