# Topological superconductivity in Ni-based transition-metal trichalcogenide superconductors

## TL;DR

This paper explores the pairing symmetries and topological properties of Ni-based transition-metal trichalcogenides using a two-orbital model, revealing nearly degenerate I-wave and chiral d-wave states with unique edge phenomena.

## Contribution

It introduces a theoretical analysis of pairing symmetries and topological states in Ni-based trichalcogenides, highlighting their potential for studying electron correlation effects.

## Key findings

- I-wave (A2g) and chiral d-wave states are dominant and nearly degenerate.
- Both states exhibit nontrivial topological properties.
- Chiral d-wave has chiral edge states; I-wave shows zero-energy Andreev bound states.

## Abstract

Based on a two-orbital honeycomb lattice model and random phase approximation, we investigate the pairing symmetry of the Ni-based transition-metal trichalcogenide. We find that an I-wave (A2g) state and a chiral d-wave state are dominant and nearly degenerate for typical electron and hole dopings. These two states carry nontrivial topological properties, which are manifested by the presence of chiral edge states in the d+id-wave state and dispersionless Andreev bound state at zero energy in the I-wave state. Ni-based transition-metal trichalcogenides provide us a new platform to study the exotic phenomena emerged from electron-electron correlation effects.