First-principles study of hydrogen-doping effects on iron-based superconductors

Nakamura, Hiroki  ; Machida, Masahiko  

Since the discovery of the iron-based superconductor, LaFeAsOF whose Tc reached 26K, various types of iron-based superconductors have been fabricated to attain higher Tc. Recently, it is reported that Tc of an iron-based superconductor LaFeAsO is enhanced to 35K by doping hydrogen. This result implies that atoms of light elements penetrate into the crystal of iron-based superconductors and transform their structures into more useful ones for superconductivity. In this paper, we investigate how the hydrogen atoms are doped in the iron-based superconductors by using the first-principles density functional theory. Furthermore, we evaluate the effects of doping on the crystal structures and electronic states and explore the origin of the Tc enhancements.