Non-Reciprocal Directional Dichroism of THz Radiation in Multiferroics in the Paramagnetic State

ORAL

Abstract

Magneto-electric (ME) effect in multiferroic (MF) materials is the cornerstone of new electronic devices allowing the electric field control of magnetization. Collective spin excitations, coupled to electric polarization, absorb THz radiation and can be used as diodes of THz radiation controlled by electric and magnetic fields [I. Kezsmarki, et al., Phys. Rev. Lett. 106, 057403 (2011)]. ME effect appears below the magnetic ordering temperature in type-II MFs. Surprisingly, in MF Sr2CoSi2O7 the dc ME effect re-appears above the magnetic ordering temperature [M. Akaki, et al., Phys. Rev. B 86, 060413 (2012)] when strong magnetic fields align the spins and create macroscopic electric polarization through the on-site ME mechanism, specific to Sr2CoSi2O7 and other compounds of this family. In this contribution we present the results of THz spectroscopy study of non-reciprocal directional dichroism (NDD) in Sr2CoSi2O7 above the Neel temperature in strong magnetic fields as a function of temperature. We show that NDD is driven by and can be linked quantitatively to the static quadratic ME effect.

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Presenters

  • Toomas Room

    National Institute of Chemical Physics & Biophysics, National Institute of Chemical Physics and Biophysics

Authors

  • Toomas Room

    National Institute of Chemical Physics & Biophysics, National Institute of Chemical Physics and Biophysics

  • Johan Viirok

    National Institute of Chemical Physics & Biophysics, National Institute of Chemical Physics and Biophysics

  • Urmas Nagel

    National Institute of Chemical Physics & Biophysics, National Institute of Chemical Physics and Biophysics

  • Daniel Farkas

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

  • David Szaller

    Institute of Solid State Physics, Vienna University of Technology

  • Istvan Kezsmarki

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

  • Peter Balla

    Institute for Solid State Physics and Optics, Wigner Research Center for Physics, Hungarian Academy of Sciences

  • Karlo Penc

    Institute for Solid State Physics and Optics, Wigner Research Center for Physics, Hungarian Academy of Sciences, Budapest University of Technology and Economics

  • Vilmos Kocsis

    RIKEN Center for Emergent Matter Science (CEMS)

  • Yusuke Tokunaga

    RIKEN Center for Emergent Matter Science (CEMS)

  • Yasujiro Taguchi

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

  • Yoshinori Tokura

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