Regensburg 2010 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 44: Materials Design II
MM 44.2: Talk
Wednesday, March 24, 2010, 16:30–16:45, H5
Superconductivity in FeSe1−x : a simple system with ambiguities — •Amir-Abbas Haghighirad, Mariano de Souza, Ulrich Tutsch, Sebastian Köhler, Daniel Hofmann, Michael Lang, and Wolf Assmus — Physikalisches Institut, Goethe-Universität, Max-von-Laue Str. 1, D-60438 Frankfurt (M), Germany
Recently, superconductivity has been reported at ∼ 8.5 K in FeSe with the α-PbO-type structure [1]. One of the interesting aspects of superconductivity in FeSe is the enormous effect of Tc [2,3] when pressure is applied. The latter indicates an extraordinarily high sensitivity of the superconducting state to structural deformations [4,5]. However, the accurate structure and the terminology for describing the FeSe phase that exhibits superconductivity is still not well understood. Several groups, as well as ours, have undertaken the effort to refine the synthesis steps to produce better quality single-crystalline samples of FeSe, which is crucial for resolving the physical properties, such as “anomalous” resistivity, the role of the structural phase transition as well as the role of magnetism in enabling superconductivity. We have improved our methods of synthesis using ambient- and high-pressure techniques. The effect of stoichiometry on the phase purity of FeSe and its superconducting properties were investigated. We will provide an overview of the progress seen so far. [1] F.C. Hsu et al., Proc. Natl. Acad. Sci. U.S.A. 105, 14262 (08); [2] K.W. Yeh et al., Europhys. Lett. 84, 37002 (08); [3] S. Medvedev et al., Nat. Mat. 8, 576 (09); [4] S. Margadonna et al., Chem. Commun. 43, 50607 (08); [5] T.M. McQueen et al., Phys. Rev. Lett. 103, 057002 (09).