Effects of heavy-ion irradiation on the microwave surface impedance of (Ba1−xKx)Fe2As2 single crystals. (14th February 2018)

• Record Type: Journal Article
• Authors: Ghigo, G; Torsello, D; Gerbaldo, R; Gozzelino, L; Laviano, F; Tamegai, T
• Is Part Of: Superconductor science & technology. Volume 31:Number 3(2018:Mar.)
• Publication Date: 2018-02-14
• Subjects: iron-based superconductors -- heavy-ion irradiation -- microwave surface impedance; 74.70.Xa -- 74.62.En -- 74.25.nn -- 78.70.-g; Superconductivity -- Periodicals; Superconductors -- Periodicals; 537.623
• DOI: 10.1088/1361-6668/aaa858
• Languages: English
• ISSNs: 0953-2048

Abstract

Abstract: The electrodynamic response of Ba1− x K x Fe2 As2 single crystals at the microwave frequencies has been investigated by means of a coplanar resonator technique, at different values of non-magnetic disorder introduced into the samples by heavy-ion irradiation. The surface impedance Z s = R s + i X s conforms to the classical skin effect above the critical temperature. Below T c, R s monotonically decreases while X s shows a peak, which evolves as a function of the irradiation fluence. The disorder-dependent Z s ( T ) curves are analyzed within a two-fluid model, suitably modified to account for a finite quasiparticle fraction at T = 0. The analysis gives, for the unirradiated crystal, quasiparticle relaxation times τ that are in good agreement with previous literature. Smaller τ values are deduced for the disordered crystals, both in the normal and in the superconducting states. The limits of application of the model are discussed.