Fermi Surface and Band Renormalization in (Sr,K)Fe$_2$As$_2$ Superconductor from Angle-Resolved Photoemission Spectroscopy

TL;DR

This study uses high-resolution ARPES to reveal the Fermi surface and band renormalization in (Sr,K)Fe$_2$As$_2$, highlighting discrepancies with calculations and emphasizing electron correlation effects.

Contribution

First direct observation of three hole-like Fermi surface sheets around Gamma in (Sr,K)Fe$_2$As$_2$ using ARPES, and identification of band renormalization effects.

Findings

Three hole-like Fermi surface sheets observed around Gamma point.

Significant band renormalization indicating strong electron correlations.

Measured band structure differs from calculations, requiring a chemical potential shift.

Abstract

High resolution angle-resolved photoemission measurements have been carried out on (Sr,K)Fe$_2$As$_2$ superconductor (Tc=21 K). Three hole-like Fermi surface sheets are clearly resolved for the first time around the Gamma point. The overall electronic structure shows significant difference from the band structure calculations. Qualitative agreement between the measured and calculated band structure is realized by assuming a chemical potential shift of -0.2 eV. The obvious band renormalization suggests the importance of electron correlation in understanding the electronic structure of the Fe-based compounds.