Journal or Book Title
Low Temperature Physics
In-plane surface Ka-band microwave impedance of optimally dopedsingle crystals of the Fe-based superconductor Ba(Fe0.926Co0.074)2As2 (Tc = 22.8 K) was measured. Sensitive sapphire disk quasi-optical resonator with high-Tc cuprate conducting endplates was developed specially for Fe-pnictide superconductors. It allowed finding temperature variation of London penetration depth in a form of power law, namely Δλ(T) ∼ Tn with n = 2.8 from low temperatures up to at least 0.6Tc consisted with radio-frequency measurements. This exponent points towards nodeless state with pairbreaking scattering, which can support one of the extended s-pairing symmetries. The dependence λ(T) at low temperatures is well described by one superconducting small-gap (Δ≅0.75 in kTc units, where k is Boltzmann coefficient) exponential dependence.
Copyright 2011 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.
American Institute of Physics
Barannik, A. A.; Cherpak, N. T.; Ni, Ni; Tanatar, Makariy A.; Vitusevich, S. A.; Skresanov, V. N.; Canfield, Paul C.; Prozorov, Ruslan; Glamazdin, V. V.; and Torokhtii, K. I., "Millimeter-wave study of London penetration depth temperature dependence in Ba(Fe0.926Co0.074)2As2 single crystal" (2011). Ames Laboratory Publications. 211.