Edge State Induced Andreev Oscillation in Quantum Anomalous Hall Insulator-Superconductor Junctions

TL;DR

This paper investigates how interference of chiral Majorana fermions in quantum anomalous Hall insulator-superconductor junctions causes conductance oscillations, revealing the interplay between edge states, chemical potentials, and phase fluctuations.

Contribution

It demonstrates the generic presence of momentum difference-induced interference of Majorana fermions and its effect on conductance oscillations in QAH-SC junctions, including phase fluctuation effects.

Findings

Conductance oscillates with edge length and chemical potential variations.

Momentum difference between Majorana fermions depends on chemical potentials.

Dynamical phase fluctuations introduce geometrical corrections to conductance.

Abstract

We study the quantum Andreev oscillation induced by interference of the edge chiral Majorana fermions in junctions made of quantum anomalous Hall (QAH) insulators and superconductors (SCs). We show two chiral Majorana fermions on a QAH edge with SC proximity generically have a momentum difference $\Delta k$, which depends on the chemical potentials of both the QAH insulator and the SC. Due to the spatial interference induced by $\Delta k$, the longitudinal conductance of QAH-SC junctions oscillates with respect to the edge lengths and the chemical potentials, which can be probed via charge transport. Furthermore, we show the dynamical SC phase fluctuation will give rise to a geometrical correction to the longitudinal conductance of the junctions.