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TT: Tiefe Temperaturen
TT 14: FV-internes Symposium ”Orbital Physics”
TT 14.4: Talk
Tuesday, March 9, 2004, 15:35–15:50, H18
Isotropic spin waves in the paramagnetic spin liquid state of FeSc2S4 — •Alexander Krimmel1, Vladimir Tsurkan1, Alois Loidl1, Michael Mücksch1,2, and Marek Koza2 — 1Institut für Physik, Univ. Augsburg, D-86159 Augsburg, Germany — 2Institut Laue Langevin, BP156, 38042 Grenoble Cedex 9, France
FeSc2S4 crystallizes in the normal cubic spinel structure with magnetic Fe2+ ions (3d6, high spin configuration, µeff=5.12 µB) on the A-site. The Jahn-Teller ions Fe2+ are orbitally frustrated. Specific heat and magnetic measurements showed no signs of long range magnetic order down to 50 mK. The ground state properties of FeSc2S4 can be described by a spin-orbit liquid. Here we report on inelastic neutron scattering experiments on polycrystalline FeSc2S4. Even at 80 K, the paramagnetic spectral response is centered around 0.6 Å−1 corresponding to the antiferromagnetic Bragg position. On cooling, a well defined isotropic magnon dispersion evolves but the system remains in a cooperative paramagnetic state without magnetic Bragg peaks. These results are discussed within a scenario of collective magnetic excitations in an orbital liquid state.