1205.4125 (T. E. Shanygina et al.)

Study of the Two-Gap Superconductivity in GdO(F)FeAs by ScS-Andreev
Spectroscopy    [PDF]

T. E. Shanygina, Ya. G. Ponomarev, S. A. Kuzmichev, M. G. Mikheev, S. N. Tchesnokov, O. E. Omel'yanovsky, A. V. Sadakov, Yu. F. Eltsev, V. M. Pudalov, A. S. Usol'tsev, E. P. Khlybov, L. F. Kulikova

Current-voltage characteristics and dynamic conductance of the superconductor - constriction - superconductor junctions in GdO(F)FeAs polycrystalline samples with critical temperatures Tc^local = 46 - 53 K were investigated. Two superconducting gaps, the large Delta_L = 10.5 +- 2 meV, and the small one Delta_S = 2.3 +- 0.4 meV were clearly observed at T = 4.2 K. The 2Delta_L/kTc^local = 5.5 +- 1 ratio gives support to the strong coupling mechanism which is responsible for the high Tc value. Temperature dependence of the large gap Delta_L(T) indicates the presence of intrinsic proximity effect (in k-space) between two superconducting condensates.

View original: http://arxiv.org/abs/1205.4125