Double Andreev reflections and double electron transmissions in a normal-superconductor-normal junction based on type-II Weyl semimetal

TL;DR

This paper investigates unique quantum transport phenomena in a type-II Weyl semimetal-based normal-superconductor-normal junction, revealing double Andreev reflections and transmissions, with potential experimental signatures in conductance behavior.

Contribution

It introduces the occurrence of double Andreev reflections and transmissions in a Weyl semimetal junction, a phenomenon not observed in normal metals or graphene.

Findings

Double Andreev reflections and transmissions occur simultaneously.

Conductance is insensitive to chemical potential.

Conductance increases with junction length.

Abstract

We study the quantum transport behavior of a normal-superconductor-normal junction based on type-II Weyl semimetal, which is arranged in the tilting direction of the Weyl semimetal. We find that both the crossed Andreev reflection and normal reflection are forbidden, while there will be double Andreev reflections and double electron transmissions for the incident electron from the semimetal side. Andreev reflections and transmissions occur both in the retro and specular directions simultaneously, symmetric about the normal of the interface but with different amplitudes, depending on the angle and energy of incident electrons. These transport processes make the junction here quite different from that based on the normal metal or graphene. In addition, the differential conductance is studied for experimental signatures. We find that the conductance is almost unaffected by the chemical potential and it is enhanced with increasing junction length.