Cuprate superconductors have attracted extensive attention due to high critical temperatures. Conventional cuprates typically contain perfect CuO2 planes which are considered as a key factor to superconductivity since the superconductivity takes place in them. However, in Ba2CuO3+δ with δ=0.2 and O-depleted CuO2 planes, superconductivity still arises even with a transition temperature as high as 73 K. Using combined density functional theory and dynamical mean-field theory (DFT+DMFT) calculations, we investigated the electronic correlation and electronic structure of Ba2CuO3.25 with alternating quasi-one-dimensional (1D) CuO planes and O-depleted CuO2 planes. We find that although different from the usual cuprates, the Cu atoms are still dominated by a 3d9 configuration and the system is of a new kind of correlated single-orbital physics. The quasi-1D CuO planes, composed of parallel Cu-O chains, are slightly hole-doped quasi-1D Mott insulator, while the O-depleted CuO2 planes are more hole doped, with a 2D correlated electronic structure, and may host superconductivity.
@article{arxiv.2507.11454,
title = {Correlated electronic structure of high-temperature superconductor Ba$_2$CuO$_{3+\delta}$},
author = {Jing-Xuan Wang and Rong-Qiang He and Zhong-Yi Lu},
journal= {arXiv preprint arXiv:2507.11454},
year = {2026}
}