Dresden 2011 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 10: Poster Session: Superconductivity
TT 10.27: Poster
Montag, 14. März 2011, 14:00–18:00, P4
Magnetic properties and superconductivity in FeSe1−x — •Stephan Knöner, Mariano de Souza, Amir Haghighirad, Sebastian Köhler, Wolf Aßmus, and Michael Lang — Physikalisches Institut, Goethe-Universität, D-60438 Frankfurt(M), Germany
The discovery of superconductivity in Fe-pnictides has attracted enormous interest to this class of materials [1]. Among these, the binary alloy FeSe1−x with Tc ≈ 8.5 K is particularly interesting due to its simple structure [2], which enables to explore the intrinsic properties of this class of superconductors. In this contribution, we report on synthesis, structural characterization, resistivity and magnetic measurements on the hitherto not explored δ′-phase of FeSe1−x [3]. In the case of samples with Fe excess as inclusions, we show that superconductivity survives despite the presence of a large saturated magnetic moment of up to 0.9µB/Fe. By an annealing process, the quality of the samples has been improved and the saturated magnetic moment is reduced dramatically to 0.1µB/Fe. Furthermore, the magnetization curves show clear presence of a hysteresis loop, typical for ferromagnets, also at temperatures below Tc. Our results indicate the robustness of superconductivity in FeSe1−x against ferromagnetic precipitations. Aspects relating to sample quality will also be discussed.
This work is part of the DFG priority program (SPP 1458).
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M. de Souza et al., Eur. Phys. J. B 77, 101 (10).