3D superconducting gap in FeSe from ARPES

TL;DR

This study uses ARPES to map the superconducting gap in FeSe across the entire Brillouin zone, revealing significant anisotropy and providing insights into pairing mechanisms and the need for refined theories.

Contribution

It provides a comprehensive momentum-resolved measurement of the superconducting gap in FeSe, including kz dependence, highlighting anisotropies and challenging existing theoretical models.

Findings

Superconducting gap shows significant anisotropy in all momentum directions.

In-plane anisotropy can be explained by nematicity or orbital-selective pairing.

kz-anisotropy indicates the need for improved theoretical understanding.

Abstract

We present a systematic angle-resolved photoemission spectroscopy study of the superconducting gap in FeSe. The gap function is determined in a full Brillouin zone including all Fermi surfaces and kz-dependence. We find significant anisotropy of the superconducting gap in all momentum directions. While the in-plane anisotropy can be explained by both, nematicity-induced pairing anisotropy and orbital-selective pairing, the kz-anisotropy requires additional refinement of theoretical approaches.