Strong correlations and the search for high-Tc superconductivity in chromium pnictides and chalcogenides

TL;DR

This paper investigates chromium pnictides and chalcogenides as potential high-temperature superconductors, analyzing their electronic correlations and instabilities through computational methods, inspired by parallels with cuprate and iron-based superconductors.

Contribution

It proposes exploring chromium-based compounds with fewer electrons than iron to find new high-Tc superconductors, supported by detailed theoretical calculations.

Findings

Electron-doped LaCrAsO shows strong correlations.

Competing magnetic interactions are present.

Nodal d-wave pairing is a plausible superconducting instability.

Abstract

Undoped iron superconductors accommodate $n=6$ electrons in five d-orbitals. Experimental and theoretical evidence shows that the strength of correlations increases with hole-doping, as the electronic filling approaches half-filling with $n=5$ electrons. This evidence delineates a scenario in which the parent compound of iron superconductors is the half-filled system, in analogy to cuprate superconductors. In cuprates the superconductivity can be induced upon electron or hole doping. In this work we propose to search for high-Tc superconductivity and strong correlations in chromium pnictides and chalcogenides with $n<5$ electrons. By means of ab-initio, slave spin and multi-orbital RPA calculations we analyse the strength of the correlations and the superconducting and magnetic instabilities in these systems with main focus on LaCrAsO. We find that electron-doped LaCrAsO is a strongly correlated system with competing magnetic interactions, being $(\pi,\pi)$ antiferromagnetism and nodal d-wave pairing the most plausible magnetic and superconducting instabilities, respectively.