Novel Copper Fluoride Analogs of Cuprates

Abstract

On the basis of the first-principles evolutionary crystal structure prediction of stable compounds in the CuF system, we predict two experimentally unknown stable phases -Cu2F5 and CuF3. Cu2F5 comprises two interacting magnetic subsystems with the Cu atoms in the oxidation states +2 and +3. CuF3 contains magnetic Cu 3+ ions forming a lattice with the antiferromagnetic coupling. We showed that some or all of Cu 3+ ions can be reduced to Cu 2+ by electron doping, as in the well known KCuF3. Significant similarities between the electronic structures calculated in the framework of DFT+U suggest that doped CuF3 and Cu2F5 may exhibit high-T c superconductivity with the same mechanism as in cuprates.

Fate of doped carriers in silver fluoride cuprate analogs

“…The above premises set the stage to dope the material and search for unconventional high-T c superconductivity, an achievement that may lead to a revolution in understanding and applications. The simplest approach would be to grow samples with fluorine non-stoichiometry, for example excess fluorine may lead to hole doped staged phases as excess oxygen [9] in cuprates and recent pro-posals for Cu fluorides [10]. By the same token, fluorine deficiency may lead to electron doping.…”