Dresden 2011 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 57: SC: Fe-based Superconductors - 122 - Thin Films
TT 57.4: Talk
Thursday, March 17, 2011, 18:00–18:15, HSZ 304
Transport properties of thin Ba(Fe,Co)2As2 film microbridges — •Dagmar Rall1,2, Konstantin Il’in1, Kazumasa Iida3, Silvia Haindl3, Fritz Kurth3, Thomas Thersleff3, Ludwig Schultz3, Bernhard Holzapfel3, Uli Lemmer2, and Michael Siegel1 — 1Institut für Mikro- und Nanoelektronische Systeme (IMS), Karlsruher Institut für Technologie, Hertzstrasse 16, 76187 Karlsruhe — 2Lichttechnisches Institut (LTI), Karlsruher Institut für Technologie, Engesserstrasse 13, 76131 Karlsruhe — 3Institute for Metallic Materials (IMW), IFW Dresden, p. o. box 270116, 01171 Dresden
The critical current density of Ba(Fe,Co)2As2 thin film microbridges was evaluated from current-voltage characteristics measured using the standard four-probe technique. The Ba(Fe,Co)2As2 films were deposited by pulsed-laser deposition on heated (La,Sr)(Al,Ta)O3 substrates and patterned by means of photolithography and ion milling. The critical current density at T = 4.2 K reaches about 3 MA/cm2. The experimentally obtained temperature dependence of the critical current density is described by (1−T/Tc)1.5 in the unexpectedly wide temperature range 0.4 < T/Tc < 1. The results can be explained in the frame of Ginzburg-Landau theory for the de-pairing critical current. The expulsion of magnetic vortices is considered as a mechanism which is responsible for overcoming Likharev’s limit for observation of the de-pairing critical current.