Specular Andreev reflection at the edge of an InAs/GaSb double quantum well with band inversion

TL;DR

This paper experimentally studies the transition from retro- to specular Andreev reflection at the edge of an InAs/GaSb quantum well with band inversion, revealing invariant anomalous behavior across different transport regimes.

Contribution

It demonstrates the transition between retro- and specular Andreev reflection in an InAs/GaSb quantum well with band inversion, linked to transport regime variations.

Findings

Observation of anomalous Andreev reflection behavior at low bias

Identification of transition from retro- to specular Andreev reflection

Invariant behavior across different transport regimes

Abstract

We experimentally investigate transport through the side junction between a niobium superconductor and the mesa edge of a two-dimensional system, realized in an InAs/GaSb double quantum well with band inversion. We demonstrate, that different transport regimes can be achieved by variation of the mesa step. We observe anomalous behavior of Andreev reflection within a finite low-bias interval, which is invariant for both transport regimes. We connect this behavior with the transition from retro- (at low biases) to specular (at high ones) Andreev reflection channels in an InAs/GaSb double quantum well with band inversion.