Andreev reflection at the edge of a two-dimensional electron system with strong spin-orbit coupling

TL;DR

This paper experimentally studies Andreev reflection at a superconductor-two-dimensional electron system junction with strong spin-orbit coupling, revealing suppression effects and signs of topological superconductivity.

Contribution

It provides the first experimental evidence linking spin-orbit coupling to Andreev reflection suppression and topological superconductivity in a narrow quantum well structure.

Findings

Suppression of Andreev reflection at low biases

Temperature and magnetic field dependence consistent with spin-orbit effects

Signs of topological superconductivity in the structure

Abstract

We experimentally investigate transport properties of a single planar junction between the niobium superconductor and the edge of a two-dimensional electron system in a narrow $In_{0.75}Ga_{0.25}As$ quantum well with strong Rashba-type spin-orbit coupling. We experimentally demonstrate suppression of Andreev reflection at low biases at ultra low temperatures. From the analysis of temperature and magnetic field behavior, we interpret the observed suppression as a result of a spin-orbit coupling. There is also an experimental sign of the topological superconductivity realization in the present structure.