12 research outputs found
Analysis of the London penetration depth in Ni-doped CaKFe4As4
We report combined experimental and theoretical analysis of superconductivity
in CaK(FeNi)As (CaK1144) for 0, 0.017 and 0.034. To
obtain the superfluid density, , the temperature dependence of the London penetration depth,
, was measured by using tunnel-diode resonator (TDR) and
the results agreed with the microwave coplanar resonator (MWR) with the small
differences accounted for by considering a three orders of magnitude higher
frequency of MWR. The absolute value of was measured by using MWR, nm, which agreed well with the NV-centers in diamond optical
magnetometry that gave nm. The
experimental results are analyzed within the Eliashberg theory, showing that
the superconductivity of CaK1144 is well described by the nodeless s
order parameter and that upon Ni doping the interband interaction increases.Comment: 8 pages, 5 figure