FeSc2S4 is a cubic spinel where orbitally active Fe$^{2+}$ ions occupy the A-site diamond sublattice. Despite a high spin (S=2) state and Curie Weiss temperature of 45~K thermodynamic measurements show no indication of a phase transition and the material has been proposed as a unique example of a spin-orbital liquid. This ground state might arise from competition between on site spin-orbit coupling and Kugel-Khomskii exchange. We report neutron scattering measurements on polycrystalline samples of FeSc2S4 which bring this picture into question. They reveal a previously unreported magnetically ordered state below 11 K. No structural distortions are visible with neutron or x-ray scattering. The effect of hydrostatic pressure on the magnetic excitation spectrum was also explored and found to be minimal.
*This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Material Sciences and Engineering, under Grant No. DEFG02-08ER46544.
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Authors
K.W. Plumb
Institute for Quantum Matter and Johns Hopkins University
Johns Hopkins University
J.R. Morey
Johns Hopkins University
J.P.C. Ruff
CHESS
Cornell Univ
CHESS, Cornell University
J. A. Rodriguez-Rivera
National Institute of Standards and Technology
NIST
NIST and Univ of Maryland
NIST Center for Neutron Research
Tyrel M. McQueen
Johns Hopkins Univ
Institute for Quantum Matter and Jonhs Hopkins University
Institute for Quantum Matter and Johns Hopkins University
Johns Hopkins University
Institute for Quantum Matter, Johns Hopkins University
S. M. Koopayeh
Institute for Quantum Matter and Johns Hopkins University
Johns Hopkins University
Johns Hopkins Univ
Institute for Quantum Matter, Johns Hopkins University
Collin Broholm
Institute for Quantum Matter, Jonhs Hopkins University, and Quantum Condensed Matter Division, Oak Ridge National Laboratories
Johns Hopkins University
Institute for Quantum Matter and Johns Hopkins University
Johns Hopkins University, Institute for Quantum Matter
