THz spectroscopy of spin waves in multiferroic LiNiPO4 in high magnetic fields

ORAL

Abstract

LiNiPO4 belongs to the family of multiferroic lithium-ortho-phosphates where correlation between magnetic and electric dipoles leads to the ac and dc magnetoelectric (ME) effect. Manifestation of the ac ME effect is non-reciprocal directional dichroism which can be probed with ME spin excitations [1]. Thus, the knowledge of the spectrum of spin excitations and their activity is crucial in understanding ME effect. We have measured the THz absorption spectra of spin excitations in single crystals of LiNiPO4 at temperatures below 4K and in high magnetic fields. In the low temperature commensurate phase we have observed magnetic-dipole, electric-dipole and simultaneously magnetic- and electric-dipole active spin waves, a two-magnon bound state, and a two-magnon continuum. Three spin flop transitions are identified for the magnetic field parallel to the magnetic easy axis. Exchange interactions and the single ion anisotropies of a mean-field spin model are determined based on the magnetic field dependence of the spin-wave excitations.

[1] Szaller et al., Phys. Rec. B 89, 184419 (2014)

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Presenters

  • Laur Peedu

    National Institute of Chemical Physics and Biophysics, Tallinn, Estonia

Authors

  • Laur Peedu

    National Institute of Chemical Physics and Biophysics, Tallinn, Estonia

  • Toomas Room

    National Institute of Chemical Physics and Biophysics, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia

  • Johan Viirok

    National Institute of Chemical Physics and Biophysics, Tallinn, Estonia

  • Urmas Nagel

    National Institute of Chemical Physics and Biophysics, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia

  • Dávid Szaller

    Institute of Solid State Physics, Vienna University of Technology, Vienna, Austria

  • Sandor Bordacs

    Department of Physics, Budapest University of Technology and Economics and MTA-BME, Department of Physics, Budapest University of Technology and Economics and MTA-BME, Budapest, Hungary

  • Istvan Kezsmarki

    Experimental Physics 5, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, Germany, Experimental Physics V, Center for Electronic Correlations and Magnetism, Augsburg, Germany, Experimental Physics 5, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, Augsburg, Germany

  • Dmytro Kamenskyi

    High Field Magnet Laboratory (HFML-EMFL), Radboud University, Nijmegen, The Netherlands

  • Vilmos Kocsis

    RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan, Center for Emergent Matter Science (CEMS), RIKEN

  • Yusuke Tokunaga

    RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan, University of Tokyo

  • Yasujiro Taguchi

    RIKEN Center for Emergent Matter Science (CEMS), RIKEN Center for Emergent Matter Science, RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan, Center for Emergent Matter Science (CEMS), RIKEN, RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan.

  • Yoshinori Tokura

    RIKEN Center for Emergent Matter Science (CEMS), RIKEN Center for Emergent Matter Science, RIKEN CEMS, RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan, Center for Emergent Matter Science (CEMS), RIKEN, Department of Applied Physics and Quantum-Phase Electronics Center, University of Tokyo, University of Tokyo, University of Tokyo and RIKEN CEMS, CEMS, RIKEN, Center for Emergent Matter Science, RIKEN, Department of Applied Physics, University of Tokyo, University of Tokyo and RIKEN-CEMS