title: Vibronic and magnetic excitations in the spin-orbital liquid state of FeSc2S4.
abstract: Inelastic neutron scattering results on the spin-orbital liquid in FeSc2S4 are presented. This sulfospinel reveals strong geometric frustration in the spin and in the orbital sector. In the present experiments the orbital liquid is evidenced by a clear spectroscopic signature of a dynamic Jahn-Teller effect with a vibronic splitting 3Gamma approximately 2 meV in agreement with theoretical estimates. The excitations of the spin liquid reveal strong dispersion and can be characterized as cooperative spin excitations in a supercooled paramagnet with a spin gap of Delta approximately 0.2 meV.
authors.affiliation: Experimentalphysik V, Center for Electronic Correlations and Magnetism, Universität Augsburg, D-86159 Augsburg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Krimmel
authors.forename: M
authors.initials: M
authors.lastname: Mücksch
authors.forename: V
authors.initials: V
authors.lastname: Tsurkan
authors.forename: M M
authors.initials: MM
authors.lastname: Koza
authors.forename: H
authors.initials: H
authors.lastname: Mutka
authors.forename: A
authors.initials: A
authors.lastname: Loidl