Coexistence of Bloch electrons and glassy electrons inCa10(Ir4As8)(Fe2−xIrxAs2)5revealed by angle-resolved photoemission spectroscopy

Abstract

Angle-resolved photoemission spectroscopy of ${\text{Ca}}_{10}({\text{Ir}}_{4}{\text{As}}_{8})({\text{Fe}}_{2\ensuremath{-}x}{\text{Ir}}_{x}{\text{As}}_{2}{)}_{5}$ shows that the Fe $3d$ electrons in the FeAs layer form the holelike Fermi pocket at the zone center and the electronlike Fermi pockets at the zone corners as commonly seen in various Fe-based superconductors. The FeAs layer is heavily electron doped and has relatively good two dimensionality. On the other hand, the Ir $5d$ electrons are metallic and glassy probably due to atomic disorder related to the Ir $5d$ orbital instability. ${\text{Ca}}_{10}({\text{Ir}}_{4}{\text{As}}_{8})({\text{Fe}}_{2\ensuremath{-}x}{\text{Ir}}_{x}{\text{As}}_{2}{)}_{5}$ exhibits a unique electronic state where the Bloch electrons in the FeAs layer coexist with the glassy electrons in the ${\text{Ir}}_{4}{\text{As}}_{8}$ layer.