First-Principles Study of Hydrogen-Doping Effects on Iron-Based Superconductors

Abstract

We investigate effects of hydrogen doping on iron-based superconductors with the use of first-principles density functional theory. The most stable location of hydrogen atoms in LaFeAsO is found to be near Fe sites, which is consistent with NMR experiments. We also evaluate optimized crystal structure distortions and their electronic states. An origin of the critical temperature enhancement is probably caused by the lattice distortions appropriate for superconductivity. Electron doping due to hydrogen may be also related to the enhancement.