Small jump of specific heat and small gap in iron pnictide superconductors

Nakai, Noriyuki; Nakamura, Hiroki  ; Ota, Yukihiro; Nagai, Yuki*   ; Hayashi, Nobuhiko*; Machida, Masahiko  

We demonstrate that a realistic multi-band model consistently explains the specific heat of typical iron-based superconductor. With density of states of each band obtained by first principle calculations, we evaluate multiple full-gap amplitudes from the angle resolved photoemission spectroscopy and successfully reproduce the specific heat. Consequently, it is found that the specific heat strongly depends density of states. In addition, the present calculations reveal that superconducting states of the iron-based pnictide are mainly characterized by two factors. One is an amplitude difference between large and small gaps, and the other is the distribution of their gap amplitudes.