# First-principles calculations of the electronic and possible topological properties of confirmed two-dimensional high Tc superconductors Nb2CoS4, Nb2CuS4, and PtN2

## TL;DR

This paper explores whether three 2D high-temperature superconductors have topological properties by analyzing their electronic band structures.

## Contribution

The study identifies possible topological features in three confirmed 2D high-Tc superconductors using first-principles calculations.

## Key findings

- Dirac-like crossings near the Fermi level were observed in all three materials without SOC.
- SOC introduced locally gapped Dirac-like crossings in PtN2 and nodal-ring features in Nb2CoS4 and Nb2CuS4.
- These findings suggest possible topologically nontrivial phases in the studied superconductors.

## Abstract

Recently, next generation two-dimensional high-Tc superconductors have attracted intense interest. Motivated by this development, we had great interests to explore whether these high-Tc superconducting monolayers has topological properties. Here, a systematic investigation of three high-temperature, two-dimensional superconductors Nb2CoS4, Nb2CuS4, and PtN2 was conducted to examine their electronic band structures. Their band structures without SOC displayed Dirac-like crossings near the Fermi level. Upon including SOC, we found virtual evidence for locally gapped Dirac-like crossings in hexagonal PtN2 and SOC-resolved nodal-ring features in the two niobium compounds. These phenomena indicated possible topologically nontrivial phases, suggesting that these high-Tc superconductors are possible candidates for the ongoing search for topological superconductivity.

Electronic band structure calculations with SOC were conducted to ascertain possible topological properties of 2D high-Tc SCs.