Superconducting Gap and Pseudogap in Sm(O$_{1-x}$F$_x$)FeAs Layered Superconductor from Photoemission Spectroscopy

TL;DR

This study uses photoemission spectroscopy to investigate the electronic structure of SmOFeAs and doped variants, revealing a possible pseudogap and details about the superconducting gap in these Fe-based superconductors.

Contribution

It provides new insights into the electronic states and pseudogap phenomena in Sm(O$_{1-x}$F$_x$)FeAs, a class of Fe-based superconductors, using high-resolution photoemission measurements.

Findings

Fermi surface around $\Gamma$ may not be gapped in the superconducting state

A 13 meV spectral feature is consistently observed

Spectral weight suppression suggests a pseudogap presence

Abstract

High resolution photoemission measurements have been carried out on non-superconducting SmOFeAs parent compound and superconducting Sm(O$_{1-x}$F$_x$)FeAs (x=0.12, and 0.15) compounds. The momentum-integrated spectra exhibit a clear Fermi cutoff that shows little leading-edge shift in the superconducting state which suggests the Fermi surface sheet(s) around the $\Gamma$ point may not be gapped in this multiband superconductors. A robust feature at 13 meV is identified in all these samples. Spectral weight suppression near E$_F$ with decreasing temperature is observed in both undoped and doped samples that points to a possible existence of a pseudogap in these Fe-based compounds.