Zhong Yong, Fan Jia-Qi, Wang Rui-Feng, Wang ShuZe, Zhang Xuefeng, Zhu Yuying, Dou Ziyuan, Yu Xue-Qing, Wang Yang, Zhang Ding, Zhu Jing, Song Can-Li, Ma Xu-Cun, Xue Qi-Kun
State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China.
Institute of Physics, National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
Phys Rev Lett. 2020 Aug 14;125(7):077002. doi: 10.1103/PhysRevLett.125.077002.
Identifying the essence of doped Mott insulators is one of the major outstanding problems in condensed matter physics and the key to understanding the high-temperature superconductivity in cuprates. We report real space visualization of Mott insulator-metal transition in Sr_{1-x}La_{x}CuO_{2+y} cuprate films that cover both the electron- and hole-doped regimes. Tunneling conductance measurements directly on the copper-oxide (CuO_{2}) planes reveal a systematic shift in the Fermi level, while the fundamental Mott-Hubbard band structure remains unchanged. This is further demonstrated by exploring the atomic-scale electronic response of CuO_{2} to substitutional dopants and intrinsic defects in a sister compound Sr_{0.92}Nd_{0.08}CuO_{2}. The results may be better explained in the framework of self-modulation doping, similar to that in semiconductor heterostructures, and form a basis for developing any microscopic theories for cuprate superconductivity.
确定掺杂莫特绝缘体的本质是凝聚态物理中主要的突出问题之一，也是理解铜酸盐高温超导性的关键。我们报道了在覆盖电子掺杂和空穴掺杂区域的Sr_{1-x}La_{x}CuO_{2+y}铜酸盐薄膜中莫特绝缘体 - 金属转变的实空间可视化。直接在氧化铜（CuO_{2}）平面上进行的隧穿电导测量揭示了费米能级的系统性移动，而基本的莫特 - 哈伯德能带结构保持不变。通过研究CuO_{2}对替代掺杂剂和姊妹化合物Sr_{0.92}Nd_{0.08}CuO_{2}中固有缺陷的原子尺度电子响应，进一步证明了这一点。结果在自调制掺杂框架下可能得到更好的解释，类似于半导体异质结构中的情况，并为发展任何关于铜酸盐超导性的微观理论奠定了基础。
