Hysteresis of THz dielectric permittivity below TNeel in CaFe2O4

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.

–

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