标题： 高温超导体Ba$_2$CuO$_{3+δ}$的关联电子结构 显示英文标题

标题： Correlated electronic structure of high-temperature superconductor Ba$_2$CuO$_{3+δ}$

摘要： 铜氧化物超导体由于具有较高的临界温度而引起了广泛的关注。常规的铜氧化物通常包含完美的CuO$_2$平面，这些平面被认为是对超导性起关键作用的因素，因为超导性正是在其中发生的。 然而，在Ba$_2$CuO$_{3+\delta}$中含有$\delta=0.2$和 O 缺乏的 CuO$_2$平面的情况下，超导性仍然出现，甚至转变温度高达 73 K。使用结合密度泛函理论和动力学平均场理论（DFT+DMFT）的计算，我们研究了Ba$_2$CuO$_{3.25}$中交替的准一维（1D）CuO 平面和O 缺乏的 CuO$_2$平面的电子相关性和电子结构。 我们发现，尽管与通常的铜氧化物不同，铜原子仍然主要处于3$d^9$ configuration配置，系统呈现出一种新型的关联单轨道物理特性。 由平行铜氧链组成的准一维铜氧平面是轻微空穴掺杂的准一维莫特绝缘体，而缺氧的铜氧$_2$平面则掺杂更多空穴，具有二维关联电子结构，可能具有超导性。 显示英文摘要

摘要： Cuprate superconductors have attracted extensive attention due to high critical temperatures. Conventional cuprates typically contain perfect CuO$_2$ planes which are considered as a key factor to superconductivity since the superconductivity takes place in them. However, in Ba$_2$CuO$_{3+\delta}$ with $\delta=0.2$ and O-depleted 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 (DFT+DMFT) calculations, we investigated the electronic correlation and electronic structure of Ba$_2$CuO$_{3.25}$ with alternating quasi-one-dimensional (1D) CuO planes and O-depleted CuO$_2$ planes. We find that although different from the usual cuprates, the Cu atoms are still dominated by a 3$d^9$ 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 insulator, while the O-depleted CuO$_2$ planes are more hole doped, with a 2D correlated electronic structure, and may host superconductivity.