Andreev reflection in edge states of time reversal invariant Landau levels

TL;DR

This paper investigates conductance behavior and Andreev reflection in edge states of time reversal invariant Landau levels, revealing quantized conductance peaks and unique signatures of superconductivity in strained honeycomb lattices.

Contribution

It introduces the concept of Andreev reflection and edge states in time reversal invariant Landau levels, highlighting their unique conductance features and valley current transport.

Findings

Conductance peaks at $4e^{2}/h$ when Landau levels are half-filled.

Presence of Andreev edge states forming electron-hole superpositions.

Identification of experimental signatures of superconductivity in these systems.

Abstract

We describe the conductance of a normal-superconducting junction in systems with Landau levels that preserve time reversal symmetry. Those Landau levels have been observed in strained honeycomb lattices. The current is carried along the edges in both the normal and superconducting regions. When the Landau levels in the normal region are half-filled, Andreev reflection is maximal and the conductance plateaus have a peak as a function of filling factor. The height of those peaks is quantized at $4e^{2}/h$. The interface of the junction has Andreev edge states, which form a coherent superposition of electrons and holes that can carry a net valley current. We identify unique experimental signatures for superconductivity in time reversal invariant Landau levels.