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arXiv · 1704.07578

Signature of multigap nodeless superconductivity in CaKFe4As4

P. K. Biswas·A. Iyo·Y. Yoshida·H. Eisaki·K. Kawashima·A. D. Hillier
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Abstract

A newly discovered family of high-Tc Fe-based superconductors, AeAFe4As4 (Ae = Ca, Sr, Eu and A = K, Rb, Cs), offers further opportunities to understand unconventional superconductivity in these materials. In this Rapid Communication, we report on the superconducting and magnetic properties of CaKFe4As4, studied using muon spectroscopy. Zero-field muon spin relaxation studies carried out on the CaKFe4As4 superconductor do not show any detectable magnetic anomaly at Tc or below, implying that time-reversal symmetry is preserved in the superconducting ground state. The temperature dependence of the superfluid density of CaKFe4As4 is found to be compatible with a two-gap s + s-wave model with gap values of 8.6(4) and 2.5(3) meV, similar to the other Fe-based superconductors. The presence of two superconducting energy gaps is consistent with theoretical and other experimental studies on this material. The value of the penetration depth at T = 0 K has been determined as 289(22) nm.

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P. K. Biswas, A. Iyo, Y. Yoshida, H. Eisaki, K. Kawashima, A. D. Hillier. 2017-04-25. Signature of multigap nodeless superconductivity in CaKFe4As4. https://doi.org/10.1103/physrevb.95.140505

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