Berlin 2012 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 23: Superconductivity: Fe-based Superconductors - Fe(Se/Te)
TT 23.3: Talk
Wednesday, March 28, 2012, 10:00–10:15, H 2053
Itinerant magnetic excitation in Rb0.8Fe1.6Se2 — •G. Friemel1, J.T. Park1, Y. Li1, V. Tsurkan2, J. Deisenhofer2, H.-A. Krug von Nidda2, A. Loidl2, A. Invanov3, B. Keimer1, and D. S. Inosov1 — 1Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany — 2Experimentalphysik V, Center for Electronic Correlations and Magnetism, Institute for Physics, Augsburg Univ., 86135 Augsburg, Germany — 3Institut Laue-Langevin, 6 rue Jules Horowitz, F-38042 Grenoble Cedex 9, France
The recently discovered superconductors AxFe2−ySe2 (A=K, Rb, Cs) concurrently exhibit strong magnetism (TN=534 K) and superconductivity (SC) with Tc=32 K. Recent reports relate the magnetic ordering to an insulating phase with a √5× √5 iron vacancy superstructure. Superconductivity, however, seems to originate from a separate phase, which possesses large electron pockets at the M point and no hole pocket at the Γ point, according to ARPES. We present investigations of the magnetic response of this phase by inelastic neutron scattering experiments. We found resonant enhancement of magnetic excitations near Q=(π,0.5π) and E=14 meV and mapped out its Q-dependence in the (HK0)-plane and out of the plane. Our results agree well with published RPA-calculations of the normal state and SC state [1], which peak at the nesting vectors of the Fermi surface seen by ARPES and which suggest a sign changing d-wave SC order parameter for this new family of superconductors.
Maier et al., Phys. Rev. B, 83, 100515, (2011).