Andreev reflection in bilayer graphene

TL;DR

This paper investigates Andreev reflection in bilayer graphene, revealing a notable conductance suppression near the superconducting gap due to the unique spinor structure of electron and hole excitations.

Contribution

It provides a theoretical analysis of conductance behavior in bilayer graphene-superconductor junctions using the Dirac-Bogoliubov-De-Gennes framework, highlighting a novel suppression effect.

Findings

Conductance suppression just below the superconducting gap

Orthogonality of reflected valence band hole and incoming electron at normal incidence

Analysis based on spinor structures of excitations

Abstract

We consider the conductance of a normal-superconductor junction in bilayer graphene in the framework of the Dirac-Bogoliubov-De-Gennes equation. A remarkable suppression of the conductance at voltages just below the superconducting gap is found. This can be understood in terms of the spinor structures of the electron and hole excitations, in particular the reflected valence band hole being orthogonal to the incoming electron at normal incidence. Minor changes in response to referee reports, references updated.