Electronic properties and doping mechanism in cuprates by first-principles calculations

The electronic properties of copper oxides represent an historical challenge for first-principles calculations, since the low-magnetization state (S=1/2) of Cu²⁺ ions is not correctly described by standard theories (such as the local-spin density functional theory). Here we present results obtained through our novel self-interaction free density functional scheme (the pseudo SIC [1]) for a range of different cuprates, with CuO₂ units arranged in 3-dimensional (CuO doped with Mn), bi dimensional (YBa₂Cu₃O_6+x), and one-dimensional (GeCuO₃) fashion. In all the cases we give a sound description of the chemistry and the electronic and magnetic properties of these systems: In CuO Mn-doping acts as a single donor and induces a simultaneous insulating-to-metal and antiferromagnetic-to ferromagnetic phase transition driven by double-exchange. In YBa₂Cu₃O_6+x the phase transition from antiferromagnetic insulating to paramagnetic metal is mainly governed by the ordering of doping oxygens in the Cu(I)-O-Cu(I) chains.