Novel copper fluoride analogs of cuprates.

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-Tc superconductivity with the same mechanism as in cuprates.