Effects of Zn substitution on the electronic structure of BaFe2As2 revealed by angle-resolved photoemission spectroscopy

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 measurement on Ba(Fe1−𝑥Zn𝑥)2As2 (Zn-122). In Zn-122, the temperature dependence of the resistivity shows a kink around 𝑇∼ 135 K, indicating antiferromagnetic order below the N ́ e el temperature of 𝑇N∼ 135 K. In fact, folded Fermi surfaces (FSs) similar to those of the parent compound have been observed below 𝑇N. 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.