Raman Scattering Study of Multiferroicity under Pressure in CoCr<sub>2</sub>O<sub>4</sub>

ORAL

Abstract

In the multiferroic phase exhibited by spinel CoCr2O4 below TS = 24K, the two contributing sublattices, Co2+ and Cr3+, are expected to be strongly coupled. With applied pressure, the coupling between the two sublattices can be enhanced, rendering the possibility of multiferroicity at temperatures higher than TS. We present a temperature and pressure dependent Raman scattering study of the magnon and phonon spectrum to elucidate the microscopic details of intersublattice interactions and spin-lattice coupling in CoCr2O4. At temperatures higher than TS, with increasing pressure (P > 30kbar), in addition to an existing T1g magnon at ambient pressure, a second magnon at lower energies is observed, which could indicate increased single-ion anisotropy or spin-spin interactions. We also observe a splitting of the triply degenerate T2g phonon, possibly indicating spin-induced lowering of crystal symmetry due to increased spin-lattice and intersublattice interactions. We are investigating whether these signatures reflect a multiferroic phase at T>TS, which would indicate that pressure can be used to tune the coupling between lattice and spin dynamics to control the multiferroic behavior in CoCr2O4.

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

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Presenters

  • 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

Authors

  • 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

  • Rebecca McAuliffe

    • Materials Science and Engineering and Frederick Seitz Materials Research Laboratory, University of Illinois Urbana Champaign

  • 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

  • Samuel Gleason

    • Physics and Frederick Seitz Materials Research Laboratory, Univ of Illinois - Urbana

  • Daniel Shoemaker

    • Materials Science and Engineering, University of Illinois at Urbana-Champaign
    • Materials Science and Engineering and Frederick Seitz Materials Research Laboratory, University of Illinois Urbana Champaign

  • 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