The silver route to cuprate analogs

TL;DR

This paper identifies AgF2 as a promising cuprate analog with similar electronic properties and strong antiferromagnetic coupling, suggesting potential for high-temperature superconductivity research.

Contribution

The study demonstrates that AgF2 has electronic parameters akin to La2CuO4 and highlights the importance of structural modifications to enhance magnetic interactions.

Findings

AgF2 exhibits electronic parameters similar to La2CuO4.

Superexchange constant in AgF2 reaches 70% of typical cuprates.

Reducing buckling in AgF2 planes could enhance antiferromagnetic coupling.

Abstract

The parent compound of high-Tc superconducting cuprates is a unique Mott state consisting of layers of spin-1/2 ions arranged on a square lattice and with a record high antiferromagnetic coupling within the layers. Compounds with similar characteristics have long been searched for. Nickelates and iridates had been proposed as cuprate analogs but so far have not reached a satisfactory similarity. Here we use a combination of experimental and theoretical tools to show that the commercial compound AgF2 is an excellent cuprate analog with remarkably similar electronic parameters to La2CuO4 but larger buckling of planes. Two-magnon Raman scattering reveals a superexchange constant which reaches 70% of that of a typical cuprate. We argue that structures that reduce or eliminate the buckling of the AgF2 planes could have an antiferromagnetic coupling that matches or surpasses the cuprates.