Dresden 2011 – scientific programme

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TT: Fachverband Tiefe Temperaturen

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

TT 57.6: Talk

Thursday, March 17, 2011, 18:30–18:45, HSZ 304

Tunnelling spectroscopy of BaFe₂As₂ / Au / PbIn thin film junctions — •Sebastian Döring¹, Stefan Schmidt¹, Frank Schmidl¹, Volker Tympel¹, Veit Grosse¹, Silvia Haindl², Kazumasa Iida², Fritz Kurth², Bernhard Holzapfel², and Paul Seidel¹ — ¹Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Helmholtzweg 5, 07743 Jena — ²IFW Dresden, Institut für metallische Werkstoffe, Helmholtzstrasse 20, 01069 Dresden

Tunnelling spectroscopy is an important tool to investigate the properties of iron-based superconductors. In contrast to commonly used point contact Andreev reflection (PCAR) technique, we fabricated hybrid superconductor / normal metal / superconductor (SNS) thin film structures, with tunable barrier thickness and area.

For the base electrode we use Ba(Fe_0.9Co_0.1)₂As₂ thin films, produced via pulsed laser deposition (PLD). A gold layer was sputtered to form the barrier, while the counter electrode material is the conventional superconductor PbIn with a T_c of 7.2 K.

For temperatures below 7.2 K the spectrum shows a subharmonic gap structure (SGS), described by an extended model of Octavio, Tinkham, Blonder and Klapwijk (OTBK), while at higher temperatures the SGS vanishes and an SN-like behaviour can be observed.