# Theoretical studies of superconductivity in doped BaCoSO

## TL;DR

This paper explores the potential for superconductivity in doped BaCoSO, a multi-orbital Mott insulator, revealing d-wave like pairing symmetry with complex orbital-dependent characteristics through theoretical models.

## Contribution

It provides the first theoretical analysis of superconductivity in doped BaCoSO using both t-J and Hubbard models, highlighting unconventional pairing symmetries and orbital effects.

## Key findings

- Superconductivity exhibits d-wave like pairing symmetry with gapless nodes.
- Orbital-dependent pairing form factors vary significantly across Fermi surfaces.
- Results are largely insensitive to doping levels.

## Abstract

We investigate superconductivity that may exist in the doped BaCoSO, a multi-orbital Mott insulator with a strong antiferromagnetic ground state. The superconductivity is studied in both t-J type and Hubbard type multi-orbital models by mean field approach and random phase approximation (RPA) analysis. Even if there is no C4 rotational symmetry, it is found that the system still carries a d-wave like pairing symmetry state with gapless nodes and sign changed superconducting order parameters on Fermi surfaces. The results are largely doping insensitive. In this superconducting state, the three t2g orbitals have very different superconducting form factors in momentum space. In particular, the intra-orbital pairing of the dx2-y2 orbital has a s-wave like pairing form factor. The two methods also predict very different pairing strength on different parts of Fermi surfaces.These results suggest that BaCoSO and related materials can be a new ground to test and establish fundamental principles for unconventional high temperature superconductivity.