Non-Reciprocal Directional Dichroism of THz Radiation in Multiferroic Sr<sub>2</sub>CoSi<sub>2</sub>O<sub>7</sub>

ORAL

Abstract

Directional dichroism (DD) is the effect when material absorbs light beams travelling in opposite direction differently. At THz frequencies DD has been found in multiferroics with magnetic and charge order. In these materials the spin waves are coupled to the oscillations of electric polarization. A spin wave acquires electric dipole activity due to optical magnetoelectric (ME) coupling and therefore interacts with the electric component of the THz radiation in addition to magnetic component.
We studied spin excitations in Sr2CoSi2O7 below 2 THz between 3 and 100 K and in magnetic fields up to 30 T. Almost one-way transparency is seen in some spin wave modes. What is more, the DD increases above the Neel temperature (7 K) in high magnetic field. This is unusual in multiferroics but is explained by the ME coupling on a single spin site [1]. This study demonstrates that DD exists in multiferroics with the single spin site ME interaction even above the magnetic ordering temperature when sufficiently strong polarizing external magnetic field is applied [2].
[1] Akaki et al., PRB 86, 060413 (2012)
[2] arXiv:1809.10207 (2018)

*This research was supported by the Estonian Ministry of Education and Research Grant IUT23-3 and by the European Regional Development Fund project TK134.

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Presenters

  • Johan Viirok

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

Authors

  • 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

  • Toomas Room

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

  • Dániel Gergely Farkas

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

  • Peter Balla

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

  • Dávid Szaller

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

  • 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

  • Bence Bernáth

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

  • Dmytro Kamenskyi

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

  • 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

  • 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

  • Karlo Penc

    • Hungarian Academy of Sciences
    • Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, Budapest, Hungary
    • Department of Physics, Budapest University of Technology and Economics and MTA-BME, Budapest, Hungary