# Pseudo-spin triplet superconductivity in transition-metal dichalcogenide monolayers and Andreev reflection in the lateral heterostructures of 2$H$-NbSe$_2$

## TL;DR

This paper explores pseudo-spin triplet superconductivity in transition-metal dichalcogenide monolayers, demonstrating its impact on electric transport and Andreev reflection in heterostructures, with numerical evidence of conductance sign changes due to doping.

## Contribution

It introduces the concept of pseudo-spin triplet superconductivity in TMD monolayers and analyzes its effects on transport properties in heterostructures, a novel insight in the field.

## Key findings

- Pseudo-spin affects electric transport in heterojunctions.
- Andreev reflection is suppressed near the valence band edge.
- Conductance sign change indicates pseudo-spin triplet pairing.

## Abstract

We study the pseudo-spin of electron pair in superconducting transition-metal dichalcogenide monolayers and show that the pseudo-spin affects the electric transport property of lateral heterojunction of the superconducting and metallic monolayers. The pseudo-spins of two electrons forming a Cooper pair are parallel to each other unlike the real spins being anti-parallel. In the lateral heterojunction, the electronic transport with forming a Cooper pair, the Andreev reflection, is suppressed with the Fermi level crossing the valence band near the edge in the metallic monolayer. We numerically investigate the electric transport property of the lateral heterojunctions of semiconducting and superconducting transition-metal dichalcogenides, MoSe$_2$ monolayer and NbSe$_2$ monolayer with the charge doping, respectively. We find the sign change of conductance difference between the normal and superconducting phases by varying the charge density and show that the sign change is resulted from the pseudo-spin triplet superconductivity.