Common Electronic Origin of Superconductivity in (Li,Fe)OHFeSe Bulk Superconductor and Single-Layer FeSe/SrTiO3 Films

TL;DR

This study reveals that a bulk FeSe-based superconductor shares electronic structure features with high-Tc single-layer FeSe/SrTiO3 films, suggesting a common electronic origin of superconductivity in these materials.

Contribution

It demonstrates that a bulk superconductor has similar electronic properties to single-layer FeSe/SrTiO3 films, providing new insights into the mechanism of high-temperature superconductivity.

Findings

Similar Fermi surface topology in bulk and monolayer materials

Nearly isotropic superconducting gap without nodes

Electronic structure insights into high-Tc superconductivity

Abstract

The mechanism of high temperature superconductivity in the iron-based superconductors remains an outstanding issue in condensed matter physics. The electronic structure, in particular the Fermi surface topology, is considered to play an essential role in dictating the superconductivity. Recent revelation of distinct electronic structure and possible high temperature superconductivity with a transition temperature Tc above 65 K in the single-layer FeSe films grown on the SrTiO3 substrate provides key information on the roles of Fermi surface topology and interface in inducing or enhancing superconductivity. Here we report high resolution angle-resolved photoemission measurement on the electronic structure and superconducting gap of a novel FeSe-based superconductor, (Li0.84Fe0.16)OHFe0.98Se, with a Tc at 41 K. We find that this single-phase bulk superconductor shows remarkably similar electronic behaviors to that of the superconducting single-layer FeSe/SrTiO3 film in terms of Fermi surface topology, band structure and nearly isotropic superconducting gap without nodes. These observations provide significant insights in understanding high temperature superconductivity in the single-layer FeSe/SrTiO3 film in particular, and the mechanism of superconductivity in the iron-based superconductors in general.