Doping-Dependent and Orbital-Dependent Band Renormalization in Ba(Fe_1-xCo_x)_2As_2 Superconductors

TL;DR

This study uses angle-resolved photoemission spectroscopy to reveal how doping levels affect the band structure and renormalization in Ba(Fe_1-xCo_x)_2As_2 superconductors, linking orbital fluctuations to superconductivity.

Contribution

It demonstrates doping- and orbital-dependent band renormalization in Fe-based superconductors, highlighting the role of Fe 3d orbital degeneracy in superconductivity enhancement.

Findings

Fe 3d yz/zx band width depends on doping level

Optimal doping causes flattening of the Fe 3d yz/zx hole band

Band renormalization correlates with increased superconducting transition temperature

Abstract

Angle resolved photoemission spectroscopy of Ba(Fe1-xCox)2As2 (x = 0.06, 0.14, and 0.24) shows that the width of the Fe 3d yz/zx hole band depends on the doping level. In contrast, the Fe 3d x^2-y^2 and 3z^2-r^2 bands are rigid and shifted by the Co doping. The Fe 3d yz/zx hole band is flattened at the optimal doping level x = 0.06, indicating that the band renormalization of the Fe 3d yz/zx band correlates with the enhancement of the superconducting transition temperature. The orbital-dependent and doping-dependent band renormalization indicates that the fluctuations responsible for the superconductivity is deeply related to the Fe 3d orbital degeneracy.