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TT: Fachverband Tiefe Temperaturen

TT 57: SC: Fe-based Superconductors - 122 - Thin Films

TT 57.4: Vortrag

Donnerstag, 17. März 2011, 18:00–18:15, HSZ 304

Transport properties of thin Ba(Fe,Co)₂As₂ film microbridges — •Dagmar Rall^1,2, 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/T_c)^1.5 in the unexpectedly wide temperature range 0.4 < T/T_c < 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.