Hysteresis of THz dielectric permittivity below T<sub>Neel</sub> in CaFe<sub>2</sub>O<sub>4</sub>

ORAL

Abstract

CaFe2O4 is a quantum antiferromagnet that exhibits an interplay between two different magnetic phases below TNeel ~ 200 K. We have analyzed the terahertz (THz) response of CaFe2O4 for the polarization configuration hω||c and eω||b and observed a significant change in the spectrum between 80 K and 120 K for frequencies above 900 GHz. The THz dielectric permittivity shows hysteresis between 80 K and 120 K that does not occur for any other orientations. In addition, we have observed a magnon with a frequency of 840 GHz at 10 K that red shifts with increasing temperature until 70 K. At which point, its spectral weight decreases rapidly, while at the same time a lower frequency magnon gains intensity. This behavior is only observed for hω||c irrespective of the direction of the electric field of the THz pulse. These behaviors seem to be associated with the decrease in the population of the B magnetic phase and simultaneous increase in the population of the A phase around 100 K.

*Funding for this research was provided by the Center for Emergent Materials: an NSF MRSEC under award number DMR-1420451.

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Presenters

  • Daniel Heligman

    • Physics, Ohio State University

Authors

  • Daniel Heligman

    • Physics, Ohio State University

  • Thuc Mai

    • Physics, Ohio State University

  • Lunyong Zhang

    • Laboratory for Pohang Emergent Materials and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science and Technology, Pohang 790-784, Korea

  • Jae Wook Kim

    • Rutgers University, New Brunswick
    • Physics and Astronomy, Rutgers University
    • Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University

  • Sang-Wook Cheong

    • Rutgers University
    • Department of Physics and Astronomy, Rutgers University
    • Rutgers University, New Brunswick
    • Rutgers Center for Emergent Materials and Department of Physics & Astronomy, Rutgers University
    • Center for Quantum Materials Synthesis and Department of Physics and Astronomy, Rutgers, the State University of New Jersey
    • Department of Physics, Rutgers University
    • Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, NJ
    • Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
    • Physics, Rutgers University
    • Physics and Astronomy, Rutgers University, New Brunswick
    • Department of Physics and Astronomy, Rutgers University, New Jersey
    • Rutgers University, Physics and Astronomy, and Laboratory for Pohang Emergent Materials and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science
    • RCEM, Department of Physics and Astronomy, Rutgers U.
    • Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University
    • Department of Physics and Astronomy, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA, Rutgers Center for Emergent Materials

  • Rolando Valdes Aguilar

    • Department of Physics, The Ohio State University
    • Physics, Ohio State University