Band Structure and Fermi Surface of an Extremely Overdoped Iron-Based Superconductor KFe2As2

TL;DR

This study uses high-resolution photoemission spectroscopy to analyze the electronic structure of heavily overdoped KFe2As2, revealing significant Fermi surface changes and implications for high-temperature superconductivity mechanisms.

Contribution

It provides detailed insights into the Fermi surface topology and band renormalization in overdoped KFe2As2, highlighting the role of electronic states around the M point in superconductivity.

Findings

Fermi surface around the zone center is similar to optimally doped compounds.

Electron pockets at the M point are absent in overdoped samples.

Electronic states near the M point are crucial for high-Tc superconductivity.

Abstract

We have performed high-resolution angle-resolved photoemission spectroscopy on heavily overdoped KFe_2As_2 (transition temperature (Tc = 3 K). We observed several renormalized bands near the Fermi level with a renormalization factor of 2-4. While the Fermi surface (FS) around the Brillouin-zone center is qualitatively similar to that of optimally-doped Ba_{1-x}K_xFe_2As_2 (x = 0.4; Tc = 37 K), the FS topology around the zone corner (M point) is markedly different: the two electron FS pockets are completely absent due to excess of hole doping. This result indicates that the electronic states around the M point play an important role in the high-Tc superconductivity of Ba$_{1-x}$K$_x$Fe$_2$As$_2$ and suggests that the interband scattering via the antiferromagnetic wave vector essentially controls the Tc value in the overdoped region.