Topologically nontrivial phases in superconducting transition metal carbides

TL;DR

This paper predicts that rock-salt VC and CrC are dynamically stable superconductors with topologically nontrivial states, making them promising candidates for topological superconductivity and Majorana fermion research.

Contribution

First principles calculations reveal that rock-salt VC and CrC are stable superconductors with topologically nontrivial states, expanding the material candidates for topological superconductivity.

Findings

VC and CrC are dynamically stable with no imaginary phonon frequencies.

Both materials exhibit soft acoustic phonon bands indicating BCS superconductivity.

They possess topologically nontrivial electronic states suitable for Majorana fermion studies.

Abstract

Topological superconductors have shown great potential in the search for unique quasiparticles such as Majorana fermions. Combining nontrivial band topology and superconductivity can lead to topological superconductivity due to the proximity effect. In this work, we used first principles calculations to predict that rock-salt phases of VC and CrC are superconducting with topologically nontrivial states. The phonon dispersions of these transition metal carbides displayed no imaginary frequencies, which suggests dynamic stability. Additionally, the presence of soft acoustic phonon bands supports the existence of Bardeen-Cooper-Schrieffer superconductivity in rock-salt VC and CrC. Therefore, these transition metal carbides are practical candidates for studying topological superconductors and their associated Majorana bound states.