Multiband Superconductivity in KCa2Fe4As4F2
摘要
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 ΔL and ΔS. Their temperature dependencies were measured from 1.5 K to Tc. The shapes 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.