Electronic Structure and Superconductivity of FeSe-Related Superconductors

TL;DR

This review discusses the electronic structure and superconductivity of FeSe-related materials, highlighting recent advances such as interface-induced high Tc in FeSe/SrTiO3 films and their implications for understanding iron-based superconductors.

Contribution

It provides a comprehensive overview of recent experimental findings on FeSe systems, emphasizing the electronic properties and interface effects relevant to high-temperature superconductivity.

Findings

Superconducting Tc of FeSe can be enhanced from 8 K to 37 K under high pressure.

FeSe/SrTiO3 films exhibit a Tc above 65 K, indicating interface superconductivity.

Substitution and intercalation modify Tc and electronic structure, revealing key factors in superconductivity.

Abstract

The FeSe superconductor and its related systems have attracted much attention in the iron-based superconductors owing to their simple crystal structure and peculiar electronic and physical properties. The bulk FeSe superconductor has a superconducting transition temperature (Tc) of ~8 K; it can be dramatically enhanced to 37 K at high pressure. On the other hand, its cousin system, FeTe, possesses a unique antiferromagnetic ground state but is non-superconducting. Substitution of Se by Te in the FeSe superconductor results in an enhancement of Tc up to 14.5 K and superconductivity can persist over a large composition range in the Fe(Se,Te) system. Intercalation of the FeSe superconductor leads to the discovery of the AxFe2-ySe2 (A=K, Cs and Tl) system that exhibits a Tc higher than 30 K and a unique electronic structure of the superconducting phase. The latest report of possible high temperature superconductivity in the single-layer FeSe/SrTiO3 films with a Tc above 65 K has generated much excitement in the community. This pioneering work opens a door for interface superconductivity to explore for high Tc superconductors. The distinct electronic structure and superconducting gap, layer-dependent behavior and insulator-superconductor transition of the FeSe/SrTiO3 films provide critical information in understanding the superconductivity mechanism of the iron-based superconductors. In this paper, we present a brief review on the investigation of the electronic structure and superconductivity of the FeSe superconductor and related systems, with a particular focus on the FeSe films.