# Anisotropic Andreev Reflection and Josephson Effect in Ballistic Phosphorene

## TL;DR

This paper investigates how anisotropic band structure in ballistic phosphorene affects Andreev reflection and Josephson supercurrent, revealing orientation-dependent behavior and control via gate voltage.

## Contribution

It demonstrates the anisotropic effects on supercurrent and Andreev reflection in phosphorene, highlighting the role of transverse modes and orientation dependence.

## Key findings

- Supercurrent varies significantly with direction in phosphorene.
- Gate voltage controls Andreev reflection probability.
- Supercurrent oscillates with junction length and chemical potential.

## Abstract

We study Andreev reflection and the Josephson effect in a ballistic monolayer of black phosphorous, known as phosphorene. Due to the anisotropic band structure of this system, the supercurrent changes with an order of magnitude when comparing tunneling along two perpendicular directions in the monolayer. We show that the main reason for this effect is a large difference in the number of transverse modes in Andreev bound states. The oscillatory behavior of the supercurrent as a function of the length and chemical potential of the junction also differs substantially depending on the orientation of the superconducting electrodes deposited on the phosphorene sheet. For Andreev reflection, we show that a gate voltage controls the probability of this process and that the anisotropic behavior found in the supercurrent case is also present for conductance spectra.