报告摘要：

　　The physics of doped Mott insulators is at the heart of some of the most exotic physical phenomena in materials research including insulator-metal transitions, colossal magneto-resistance. These phenomena often emerge as a function of carrier doping and are rooted in the strongly correlated motion of the charge carriers and their coupling to lattice and magnetic excitations of the crystal. Here I report two parts of our recent work on the doping of a simple 2D Mott insulating system: an ordered (Ö3´Ö3)R30° lattice formed by 1/3 ML Sn adatoms adsorbed on the Si(111) surface with half-filled dangling bond orbitals. The first part is about electron doping with potassium atoms. 1/6 ML K atoms adsorbed on the surface forms a sublattice and induces a charge ordered phase in the Sn lattice. As the temperature rises, the K sublattice gradually melts and induces a series of phase transitions in the charge ordered Sn lattice. The second part if about hole doping by introducing boron dopants to the subsurface layer of the Si substrate. Hole doping metalize the Mott insulating Sn lattice, while low temperature STM/STS shows that it becomes superconducting with a critical temperature of 4.7±0.3 K. Mott correlations in the Sn-derived dangling-bond surface state suggests that the superconductivity might be unconventional.

References:

[1]T. Smith, F. Ming, et al., PRL 124, 097602 (2020)

[2]X. Wu, F. Ming, et al., PRL, 125, 117001 (2020)

报告人简介

　　明方飞 博士，现任中山大学电子与信息工程学院副教授。2007年本科毕业于西北大学（西安），2012年获香港中文大学物理学博士学位，2012年8月到2014年2月在香港中文大学从事博士后研究工作，2013年7月到2014年4月在中国科学技术大学做访问研究，2014年5月起在田纳西大学诺克斯维尔分校做博士后。2018年9月加入中山大学电子与信息工程学院、广东省显示材料重点实验室。主要从事低维材料，凝聚态物理，原子、分子尺度的纳米结构及其电学性质等方面的实验研究。