Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 27: Superconductivity: Fe-based Superconductors - 122
TT 27.11: Vortrag
Dienstag, 12. März 2013, 12:30–12:45, H18
Strain induced bulk superconductivity in BaFe2As2 thin films — •Jan Engelmann1,2, Paul Chekhonin2, Werner Skrotzki2, Ruben Hühne1, Fritz Kurth1,2, Silvia Haindl1, Kazumasa Iida1, Ludwig Schultz1,2, Holzapfel Bernhard1,3, and Grinenko Vadim1 — 1IFW Dresden, P. O. Box 270116, 01171 Dresden, Germany — 2Dresden University of Technology, Department of Physics, 01062 Dresden, Germany — 3TU Bergakademie Freiberg, 09596 Freiberg, Germany
We report superconductivity in non-doped BaFe2As2 (Ba122) thin films grown on Fe buffered Spinel single crystalline substrates. Superconductivity was achieved in our thin films by varying the thickness of the Ba122. Increasing the thickness to a critical value of approximately 10 nm results in an increase of the superconducting critical temperature to Tc=28 K whereas films with a thickness of >100 nm do not show any superconductivity. We connect this appearance of superconductivity with the inclusion of strain in our samples. Very thin samples are fixed to the Fe buffer layer and substrate lattice constant (increased a-axis lattice constant and shortened c-axis lattice constant) whereas with increasing thickness the Ba122 layer relaxes to its bulk values. We will present via X-ray analysis the relaxation of the c-axis lattice constant coming along with structural changes showed via transmission electron microscopy (TEM) and atomic force microscopy (AFM). The bulk nature of superconductivity was determined by measurements of the critical current density and via magnetic measurements using a SQUID.