<研究ノート>鉄系超伝導体BaFe2(As_{1-x}P)2 のフェルミ面と超伝導ギャップ異方性

Abstract

Fermi surfaces and superconducting gaps of iron-based superconductor BaFe2(As1-xPx)2 have been investigated by angle-resolved photoemission spectroscopy. We found that one of the hole Fermi surfaces has highly three-dimensional shape. Moderately strong electron mass enhancement has been identified for both the electron and hole Fermi surfaces. As for the superconducting gaps, strongly anisotropic gap has been found only in the electron Fermi surface while the gap on the entire hole Fermi surfaces are nearly isotropic. These results can be theoretically reproduced by considering both spin and orbital fluctuations. This suggests that both fluctuations are equally important for the high-Tc superconductivity in this system.