Regensburg 2007 – scientific programme
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MA: Fachverband Magnetismus
MA 13: Spinstructures and magnetic Phase Transitions
MA 13.11: Talk
Tuesday, March 27, 2007, 12:45–13:00, H5
Neutron Scattering on the Spin-Orbit Liquid State of FeSc2S4 — •Michael Mücksch1,2, Alexander Krimmel1, Vladimir Tsurkan1,3, Denis Sheptyakov4, Michael Marek Koza2, Amir Murani2, Hannu Mutka2, Siegfried Horn1, and Alois Loidl1 — 1Institute of Physics, University of Augsburg, D-86159 Augsburg, Germany — 2Institute Laue Langevin, F-38042 Grenoble, France — 3Institute of Applied Physics, Academy of Sciences of Moldova, MD-2028 Chisinau, R. Moldova — 4Laboratory for Neutron Scattering, ETH Zürich & PSI, CH-5232 Villigen PSI, Switzerland
The developement of the spin-orbital liquid ground state in the normal cubic spinel compound FeSc2S4[1] based on the electronic degenerate magnetic Fe2+ (3d6) ions is studied by extensive neutron scattering studies. The dynamic structure factor S(Q,ω) as obtained by neutron time-of-flight measurements exhibits at 300 K a paramagnetic quasielastic contribution, which evolves below about 120 K into a broad excitation band centered around 2 meV with a softening at particular Q - positions. This indicates a dynamic Jahn-Teller effect including spin-orbit coupling and magnetic exchange [2]. Implications on the neutron derived phonon spectra will be discussed. The magnetic excitation spectra, and in particular the gap value, are not affected by either cooling down to 200 mK or applying an external field of 2.5 T. The resolution limited elastic scattering shows a remaining paramagnetic contribution, but no changes on cooling down to 200mK, thus excluding spin glass freezing. This demonstrates the dynamic character of the ground state in FeSc2S4.[1] V. Fritsch et al., Phys. Rev. Lett. 92 (2004) 116401.[2] A. Krimmel et al., Phys. Rev. Lett. 94 (2005)237402.