Raman Scattering Study of the Low Temperature, High Pressure Structural Transition in CoV<sub>2</sub>O<sub>4</sub>

ORAL

Abstract

At ambient pressures, CoV2O4 exists very near a critical value of the vanadium-vanadium separation, rV-V = 2.94 Å, for the AV2O4 spinels, below which the electronic character transitions from insulating or semiconducting to metallic. CoV2O4 has not been shown to undergo a symmetry lowering phase change at low temperatures, unlike most other AV2O4 spinels. The cubic structure has been predicted to be stable at high pressures, despite well-known strong coupling between spin, lattice, and electronic degrees of freedom in spinels. We studied the triply degenerate 192 cm-1 phonon mode with Raman spectroscopy to determine if the cubic phase remains stable at low temperatures and if there is a structural phase change associated with the pressure-induced semiconductor-metal transition. We find no evidence for a structural transition at low temperatures at ambient pressure. However, at low temperatures and above P~4 GPa, we observe a splitting of the phonon mode, indicative of a lower symmetry phase near the semiconductor-metal phase boundary. These results provide evidence that strong spin-lattice coupling plays an essential role in the pressure-tuned semiconductor-metal transition of CoV2O4.

*Research was supported by the National Science Foundation under Grant NSF DMR 1464090.

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Presenters

  • John Slimak

    • Physics and Frederick Seitz Materials Research Laboratory, Univ of Illinois - Urbana
    • Dept. of Physics and Materials Research Laboratory, University of Illinois, Urbana-Champaign

Authors

  • John Slimak

    • Physics and Frederick Seitz Materials Research Laboratory, Univ of Illinois - Urbana
    • Dept. of Physics and Materials Research Laboratory, University of Illinois, Urbana-Champaign

  • Taylor Byrum

    • Physics and Frederick Seitz Materials Research Laboratory, Univ of Illinois - Urbana
    • Dept. of Physics and Materials Research Laboratory, University of Illinois, Urbana-Champaign

  • Astha Sethi

    • Physics and Frederick Seitz Materials Research Laboratory, Univ of Illinois - Urbana
    • Dept. of Physics and Materials Research Laboratory, University of Illinois, Urbana-Champaign

  • Haidong Zhou

    • Physics and Astronomy, Univ of Tennessee, Knoxville
    • Physics and Astronomy, University of Tennessee Knoxville
    • Department of Physics and Astronomy, University of Tennessee
    • Department of Physics and Astronomy, University of Tennessee Knoxville
    • Department of Physics & Astronomy, University of Tennessee
    • University of Tennessee
    • Physics and Astronomy, University of Tennessee
    • Physics, University of Tennessee
    • Univ of Tennessee, Knoxville
    • Physics and Astronomy, University of Tennessee, knoxville
    • Dept. of Physics and Astronomy, University of Tennessee

  • Lance Cooper

    • Physics and Frederick Seitz Materials Research Laboratory, Univ of Illinois - Urbana
    • Dept. of Physics and Materials Research Laboratory, University of Illinois, Urbana-Champaign
    • University of Illinois Urbana-Champaign