Cuprate superconductors have attracted extensive attention due to high critical temperatures. Conventional cuprates typically contain perfect ${\mathrm{CuO}}_2$ planes, which are considered as a key factor to superconductivity since the superconductivity takes place in them. However, in ${\mathrm{Ba}}_2{\mathrm{CuO}}_{3+\delta }$ with $\delta =0.2$ and O-depleted ${\mathrm{CuO}}_2$ planes, superconductivity still arises even with a transition temperature as high as 73 K. Using combined density functional theory and dynamical mean-field theory calculations, we investigated the electronic correlation and electronic structure of ${\mathrm{Ba}}_2{\mathrm{CuO}}_{3.25}$ with alternating quasi-one-dimensional (quasi-1D) CuO planes and O-depleted ${\mathrm{CuO}}_2$ planes. We find that although different from the usual cuprates, the Cu atoms are still dominated by a $3d^9$ 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 insulators, while the O-depleted ${\mathrm{CuO}}_2$ planes are more hole doped, with a two-dimensional correlated electronic structure, and may host superconductivity.

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• Density of states
• First-principles calculations
• Magnetic susceptibility
• High-temperature superconductors
• Strongly correlated systems
• Unconventional superconductors
• Density functional theory
• Dynamical mean field theory
• Electron-correlation calculations
• Non-Fermi-liquid theory