Multiband superconductivity in KCa2Fe4As4F2
A. V. Sadakov, A. A. Gippius, A. T. Daniyarkhodzhaev, A. V. Muratov, A. V. Kliushnik, O. A. Sobolevskiy, V. A. Vlasenko, A. I. Shilov, K. S. Pervakov
Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia
Abstract
The paper reports complementary studies of the order parameter of the newly discovered iron-based superconductor,KCa2Fe4As4F2 (Tc
= 34 K),that consists of alternating blocks of KFe2As2 (122) phase and CaFeAsF (1111) phase.We performed high-resolution intrinsic multiple Andreev reflection spectroscopy supplemented with self-field critical current measurements.Andreev spectra,obtained by means of a break-junction technique reveal two distinct superconducting order parameters - ?L and ?S.Their temperature dependencies were measured from 1.5 K to Tc.The shape of Andreev reflections dips,corresponding to the two gaps,are symmetrical,which is a signature of s-wave order parameter.Temperature dependence of the self-field critical current can also be described by two s-wave gaps model.