摘要
We perform systematic thermal conductivity measurements on heavily hole-doped Ba1-xKxFe2As2 single crystals with 0.747 ≤ x ≤ 0.974. At x=0.747, the K0/T is negligible, indicating a nodeless superconducting gap. A small residual linear term K0/T （=0.035 m W.K-2 cm-1） appears at xz0.826, and it increases slowly up to x=0.974, followed by a substantial increase of more than 20 times to of K0/T clearly shows that the nodal gap appears near x surface topology. The small values of K0/T from x=0.826 the pure KFe2As2 （x=1.0）. This doping dependence = 0.8, possibly associated with the change of Fermi to 0.974 are consistent with the Y-shaped nodal s- wave gap recently revealed by angle-resolved photoemission spectroscopy experiments at x=0.9. Furthermore, the substantial increase of K0/T from x=0.974 to 1.0 is inconsistent with a symmetry-imposed d-wave gap in KFe2 As2, and a possible nodal gap structure in KFe2As2 is discussed.
We perform systematic thermal conductivity measurements on heavily hole-doped Ba1-xKxFe2As2 single crystals with 0.747 ≤ x ≤ 0.974. At x=0.747, the K0/T is negligible, indicating a nodeless superconducting gap. A small residual linear term K0/T （=0.035 m W.K-2 cm-1） appears at xz0.826, and it increases slowly up to x=0.974, followed by a substantial increase of more than 20 times to of K0/T clearly shows that the nodal gap appears near x surface topology. The small values of K0/T from x=0.826 the pure KFe2As2 （x=1.0）. This doping dependence = 0.8, possibly associated with the change of Fermi to 0.974 are consistent with the Y-shaped nodal s- wave gap recently revealed by angle-resolved photoemission spectroscopy experiments at x=0.9. Furthermore, the substantial increase of K0/T from x=0.974 to 1.0 is inconsistent with a symmetry-imposed d-wave gap in KFe2 As2, and a possible nodal gap structure in KFe2As2 is discussed.
基金
Supported by the National Basic Research Program under Grant Nos 2012CB821402 and 2015CB921401
the National Natural Science Foundation of China
the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning
STCSM of China(No 15XD1500200)
