Insulating Parent Phase and Distinct Doping Evolution to Superconductivity in Single-Layer FeSe/SrTiO3 Films
Abstract
The single-layer FeSe/SrTiO3 (FeSe/STO) films have attracted much attention because of their simple crystal structure, distinct electronic structure and record high superconducting transition temperature (Tc). The origin of the dramatic Tc enhancement in single-layer FeSe/STO films and the dichotomy of superconductivity between single-layer and multiple-layer FeSe/STO films are still under debate. Here we report a comprehensive high resolution angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy measurements on the electronic structure evolution with doping in single-layer and multiple-layer FeSe/STO films. We find that the single-layer FeSe/STO films have a distinct parent phase and a route of doping evolution to superconductivity that are fundamentally different from multiple-layer FeSe/STO films. The parent phase of the single-layer FeSe/STO films is insulating, and its doping evolution is very similar to that of doping a Mott insulator in cuprate superconductors. In multiple-layer FeSe/STO films, high-Tc superconductivity occurs by suppressing the nematic order in the parent compound with electron doping. The single-layer FeSe/STO films represent the first clear case in the iron-based superconductors that the parent compound is an insulator. Our observations of the unique parent state and doping evolution in the single-layer FeSe/STO films provide key insight in understanding its record high-Tc superconductivity. They also provide a new route of realizing superconductivity in iron-based superconductors that is common in high temperature cuprate superconductors.
Cite
@article{arxiv.1904.04662,
title = {Insulating Parent Phase and Distinct Doping Evolution to Superconductivity in Single-Layer FeSe/SrTiO3 Films},
author = {Yong Hu and Yu Xu and Yi-Min Zhang and Qing-Yan Wang and Shao-Long He and De-Fa Liu and Ai-Ji Liang and Jian-Wei Huang and Cong Li and Yong-Qing Cai and Ding-Song Wu and Guo-Dong Liu and Fang-Sen and Jia-Qi Fan and Guan-Yu Zhou and Lili Wang and Can-Li Song and Xu-Cun Ma and Qi-Kun Xue and Zu-Yan Xu and Lin Zhao and X. J. Zhou},
journal= {arXiv preprint arXiv:1904.04662},
year = {2022}
}