报告题目：Visualizing the atomic and molecular orbital basis for pair formation in cuprate

报告时间：2024年4月25日（周四）14:00

报告地点：鼓楼校区唐仲英楼 B501

报  告 人：王亚愚，清华大学

摘要：

The parent compound of cuprate high temperature superconductors is a charge-transfer-type Mott insulator with strong hybridization between the Cu 3d_x2-y2 and O 2p orbitals. A key question concerning the pairing mechanism is the behavior of doped holes in the antiferromagnetic (AF) Mott insulator background, which is a prototypical quantum many-body problem. Scanning tunneling microscopy (STM) represents an ideal experimental technique to address these questions owing to its capability of atomic-scale imaging of local electronic states.

In this work, we use STM to visualize the electronic structure of diluted holes doped into the Ca₂CuO₂Cl₂ parent Mott insulator of cuprates. We find that a single hole exhibits an in-gap electronic state and clover-shaped spatial distribution reminiscent of an extended d_x2-y2 atomic orbital. For multiple dopants lying in close proximity, the overlap of wavefunctions generates stripe- and ladder-shaped molecular orbitals, accompanied by the opening of a precursory energy gap around the Fermi level. With increasing doping, the molecular patterns proliferate in space and gradually form densely packed plaquettes with characteristic length scale around 4 a₀. A full-fledged superconducting gap develops smoothly on top of the molecular orbitals, and display a systematic evolution of gap function. These results demonstrate that the stripe-like molecular orbital is the first low energy electronic state induced by doping the antiferromagnetic Mott insulator, and a local Cooper pair is formed by two holes occupying a molecular plaquette.

报告人简介：

    王亚愚，1998年本科毕业于中国科技大学物理系，2004年在普林斯顿大学物理系获得博士学位，2004-2007年在加州大学伯克利分校任Miller Fellow，2007年12月加入清华大学物理系任教至今。主要从事凝聚态物理实验研究，在拓扑量子材料的输运性质和高温超导体的微观电子结构等领域取得系统性研究成果。曾获得2006年William McMillan Award、2013年低温物理学会“马丁-伍德爵士中国奖”、2015年中国物理学会“黄昆物理奖”、2018年国家自然科学一等奖（第二完成人）、2019年腾讯“科学探索奖”、2023年入选“新基石研究员”项目。

主办：南京大学物理学院、江苏省物理学会

联系人：王雷，leiwang@nju.edu.cn