Berlin 2012 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
TT: Fachverband Tiefe Temperaturen
TT 29: Superconductivity: Tunnelling, Josephson Junctions, SQUIDs 1
TT 29.10: Talk
Wednesday, March 28, 2012, 17:45–18:00, H 2053
Carrier injection into pnictide superconductors — •C. Steiner1, S. Probst1, Y. Simsek1, Y. Koval1, S. Wurmehl2, B. Büchner2, and P. Müller1 — 1Department of Physics and Interdisciplinary Center of Molecular Materials, Universität Erlangen-Nürnberg — 2Institute for Solid State Research, IFW-Dresden
1111 pnictides have a layered structure consisting of FeAs planes separated by LaO layers. Doping is achieved by partial replacement of oxygen by fluorine. We have already shown that layered high-Tc cuprates can be doped by carrier injection along c-axis direction [1]. For our c-axis transport measurements of pnictides we selected very small single crystals (approximately 5 × 5 × 1 µ m3) from powder samples of LaO1−xFxFeAs with x = 0.06 and x = 0.1. Mesa structures were prepared by electron beam lithography. Above a certain bias threshold, low temperature IV characteristics showed switching from a low resistive state to a high resistive state and back, indicating charge carrier trapping and release. By this type of switching, the resistance at Tc was changed approximately by a factor of 2. The c-axis critical current belonging to the low resistive state was higher by a similar ratio. This increase of critical current was accompanied by a Tc increase of ca. 2 K. We interpret these results by electron trapping in the LaO layers and compensation of this additional charge by a decrease of electron concentration in the FeAs layers.
Y. Koval, X. Y. Jin, C. Bergmann, Y. Simsek, L. Özyüzer, P. Müller, H. B. Wang, G. Behr, B. Büchner Appl. Phys. Lett. 2010, 96, 082507