Effects of Zn substitution on the electronic structure of BaFe$_2$As$_2$ revealed by angle-resolved photoemission spectroscopy

TL;DR

This study investigates how Zn substitution affects the electronic structure of BaFe₂As₂ using angle-resolved photoemission spectroscopy, revealing impurity effects and deviations from simple electron doping models.

Contribution

It provides experimental insights into the electronic structure changes due to Zn substitution, highlighting impurity potential effects and electron localization in Fe-based superconductors.

Findings

Folded Fermi surfaces observed below T_N similar to parent compound

Extra electrons from Zn do not participate in Fermi surface formation

Electronic structure deviates from rigid-band model expectations

Abstract

In Fe-based superconductors, electron doping is often realized by the substitution of transition-metal atoms for Fe. In order to investigate how the electronic structure of the parent compound is influenced by Zn substitution, which supplies nominally four extra electrons per substituted atom but is expected to induce the strongest impurity potential among the transition-metal atoms, we have performed an angle-resolved photoemission spectroscopy measurements on Ba(Fe_{1-x}Zn_x)_2As_2 (Zn-122). In Zn-122, the temperature dependence of the resistivity shows a kink around T~135 K, indicating antiferromagnetic order below the Neel temperature of T_N ~ 135 K. In fact, folded Fermi surfaces (FSs) similar to those of the parent compound have been observed below T_N. The hole and electron FS volumes are, therefore, different from those expected from the rigid-band model. The results can be understood if all the extra electrons occupy the Zn 3d state ~10 eV below the Fermi level and do not participate in the formation of the FSs.