Session 1-3

Abstract

Since the discovery of superconductivity at T_c = 26 K in LaFeAs(O_1-xF_x) in 2008 [1], iron-based superconductors have been studied extensively. T_c can be raised up to 56 K by substituting La with smaller rare-earth elements in this original 1111 structure. There are now various structure types of iron-based superconductors: the 122-type (e.g., BaFe₂As₂); 111-type (e.g., LiFeAs); 11-type (e.g., FeSe) structures and so on (see for a review [2]).
Since superconducting pairing occurs on the Fermi surface, detailed knowledge of the Fermi surface is a prerequisite for the elucidation of pairing mechanisms in superconductors. We have employed quantum-oscillation measurements to study the fermiology of iron-based superconductors and their parent compounds, i.e., KFe₂As₂ [3], BaFe₂As₂ [4], FeSe [5], FeS [6], and CaFeAsF [7]. In this talk, I will review those researches. Intriguingly, standard band-structure calculations fail to give satisfactory description of the Fermi surface in some compounds such as KFe₂As₂ and FeSe.