Electronic Physics and Possible Superconductivity in Layered Orthorhombic Cobalt Oxychalcogenides

TL;DR

This paper explores layered cobalt oxychalcogenides as strongly correlated multi-orbital systems that may host high-temperature unconventional superconductivity, differing from cuprates and iron-based superconductors due to their unique symmetry properties.

Contribution

It derives a low energy effective model for these materials and predicts the emergence of a d-wave-like superconducting state upon suppression of antiferromagnetic order.

Findings

Parental compounds are antiferromagnetic Mott insulators.

Doping leads to low energy physics dominated by three t2g orbitals.

A high-temperature d-wave-like superconducting state is predicted.

Abstract

We suggest that Cobalt-Oxychalcogenide layers constructed by vertex sharing CoA$_2$O$_2$ (A=S,Se,Te) tetrahedra, such as BaCoAO, are strongly correlated multi-orbital electron systems that can provide important clues on the cause of unconventional superconductivity. Differing from cuprates and iron-based superconductors, these systems lack of the C$_4$ rotational symmetry. However, their parental compounds possess antiferromagnetic(AFM) Mott insulating states through pure superexchange interactions and the low energy physics near Fermi surfaces upon doping is also attributed mainly to the three t$_{2g}$ orbitals that dominate the AFM interactions. We derive a low energy effective model for these systems and predict that a d-wave-like superconducting state with reasonable high transition temperature can emerge by suppressing the AFM ordering even if the pairing symmetry can not be classified by the rotational symmetry any more.