Sheet Dependence on Superconducting Gap in Oxygen-Deficient Iron-based Oxypnictide Superconductors NdFeAs0.85

TL;DR

This study uses photoemission spectroscopy to investigate how the superconducting gap in oxygen-deficient NdFeAsO0.85 varies with photon energy, revealing gap opening on electron-like Fermi surface sheets around M point.

Contribution

It demonstrates photon-energy dependence of electronic structure and identifies the specific Fermi surface sheets where the superconducting gap opens in NdFeAsO0.85.

Findings

Superconducting gap is observed on electron-like sheets around M point.

Photon energy affects the visibility of the superconducting gap.

Gap opening is not on hole-like sheets around Gamma point.

Abstract

Photoemission spectroscopy with low-energy tunable photons on oxygen-deficient iron-based oxypnictide superconductors NdFeAsO0.85 (Tc=52K) reveals a distinct photon-energy dependence of the electronic structure near the Fermi level (EF). A clear shift of the leading-edge can be observed in the superconducting states with 9.5 eV photons, while a clear Fermi cutoff with little leading-edge shift can be observed with 6.0 eV photons. The results are indicative of the superconducting gap opening not on the hole-like ones around Gamma (0,0) point but on the electron-like sheets around M(pi,pi) point.