First Principles Calculations of Solute-Hole Interactions in the High Tc Oxyfluoride Superconductor Sr2CuO2F2

Abstract

First principles periodic Hartree-Fock calculations are reported of the electronic and magnetic structures and hole states in the T (La₂CuO₄) phases of Sr₂CuO₂F₂, Sr₂CuO₂F_2.5 and NaSrCuO₂F₂. Sr₂CuO₂F₂ is predicted to be a highly ionic antiferromagnetic charge transfer insulator with Cu in a d⁹ ((d_x²_–y²)¹) configuration. Holes are predicted to be highly localised spin polarons which destroy the AF ordering at concentrations of 0.5 per formula unit.