Novel copper fluoride analogs of cuprates

Abstract

On the basis of the first-principles evolutionary crystal structure prediction of stable compounds in the Cu–F system, we predict two experimentally unknown stable phases – Cu₂F₅ and CuF₃. Cu₂F₅ comprises two interacting magnetic subsystems with Cu atoms in the oxidation states +2 and +3. CuF₃ contains magnetic Cu³⁺ ions forming a lattice by antiferromagnetic coupling. We showed that some or all of Cu³⁺ ions can be reduced to Cu²⁺ 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.