We report on the introduction of columnar defects in Ba1−x K x Fe2As2 and BaFe2(As1−x P x )2 single crystals via 1.2 GeV Pb irradiation. Scanning transmission electron microscopy analysis proves the formation of continuous defects along the ion tracks, with a diameter of about 3 nm, and a planar density compatible with the irradiation fluence. The twofold role of such defects, i.e. as pair breakers as well as pinning centers, is investigated by a microwave technique, allowing us to determine critical temperature T c , surface impedance and penetration depth λ L , and by magneto-optical imaging and superconducting quantum interference device magnetometry to evaluate the critical current density J c . The decrease of T c is quite modest and, together with λ L modifications, testifies the increase of pair-breaking scattering following irradiation. The dependence of J c on irradiation dose and temperature is due to the pinning landscape induced by the columnar defects, and shows the existence of an optimal irradiation dose to enhance the critical current.
Twofold role of columnar defects in iron based superconductors / Torsello, D; Gerbaldo, R; Gozzelino, L; Laviano, F; Takahashi, A; Park, A; Pyon, S; Ichinose, A; Tamegai, T; Ghigo, G. - In: SUPERCONDUCTOR SCIENCE & TECHNOLOGY. - ISSN 0953-2048. - ELETTRONICO. - 33:9(2020), p. 094012.
|Titolo:||Twofold role of columnar defects in iron based superconductors|
|Data di pubblicazione:||2020|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1088/1361-6668/aba350|
|Appare nelle tipologie:||1.1 Articolo in rivista|
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