Silver route to cuprate analogs

The parent compound of high-Tc superconducting cuprates is aunique Mott insulator consisting of layers of spin-1=2 ions forminga square lattice and with a record high in-plane antiferromagneticcoupling. Compounds with similar characteristics have longbeen searched for without success. Here, we use a combinationof experimental and theoretical tools to show that commercialAgF2 is an excellent cuprate analog with remarkably similarelectronic parameters to La2CuO4 but larger buckling of planes.Two-magnon Raman scattering and inelastic neutron scatteringreveal a superexchange constant reaching 70% of that of a typicalcuprate. We argue that structures that reduce or eliminatethe buckling of the AgF2 planes could have an antiferromagneticcoupling that matches or surpasses the cuprates.