Possible role of bonding angle and orbital mixing in iron pnictide superconductivity: Comparative electronic structure studies of LiFeAs and Sr2VO3FeAs

Abstract

A well-known universal feature among iron pnictide superconductors is the correlation between the As-Fe-As bonding angle and the superconducting transition temperature. However, the origin of such a correlation has not been clearly understood despite its potential importance in understanding the mechanism of superconductivity. Here, we present comparative electronic structure studies of LiFeAs and Sr2VO3FeAs, two representative systems without any dopant that can show bonding angle dependence of the electronic structure. Captured distinct features of the higher T-c compound Sr2VO3FeAs such as an unusual kz modulation and anomalous polarization dependence suggest that the difference between the two systems is in the interorbital coupling strength. This could be the essential element of the bonding angle dependence that allows an enhanced pairing instability and T-c.