Different doping from apical and planar oxygen vacancies in Ba2CuO4−δand La2CuO4−δ: First-principles band structure calculations

Abstract

First-principles band structure calculations for large supercells of Ba${}_{2}$CuO${}_{4\ensuremath{-}\ensuremath{\delta}}$ and La${}_{2}$CuO${}_{4\ensuremath{-}\ensuremath{\delta}}$ with different distributions and concentrations of oxygen vacancies show that the effective doping on copper sites strongly depends on where the vacancy is located. A vacancy within the Cu layer produces a weak doping effect while a vacancy located at an apical oxygen site acts as a stronger electron dopant on the copper layers and gradually brings the electronic structure close to that of La${}_{2\ensuremath{-}x}$Sr${}_{x}$CuO${}_{4}$. These effects are robust and only depend marginally on lattice distortions. Our results show that deoxygenation can reduce the effect of traditional La/Sr or La/Nd substitutions. Our study clearly identifies location of the dopant in the crystal structure as an important factor in doping of the cuprate planes.