Optical spectroscopy of the Triangular Lattice Antiferromagnets CuCrO$_2$ and $\alpha$-CaCr$_2$O$_4$

ORAL

Abstract

We will compare and discuss our results obtained by optical spectroscopy on CuCrO$_2$ and $\alpha$-CaCr$_2$O$_4$. While CuCrO$_2$ is famous for its multiferroicity [1], in $\alpha$-CaCr$_2$O$_4$ a polarization can only be observed under the application of electric or magnetic field, despite having a closely related structure [2]. At near infrared and visible light frequencies we observe Cr$^{3+}$ crystal field absorptions and below T$_N$ excitons and exciton-magnon-transitions appear. The width of these exciton-magnon transitions is analyzed with respect to the existence of Z$_2$ vortices as proposed by Kojima et al. [3]. \\[4pt] [1] S. Seki et al., Phys. Rev. Lett. 101, 067240 (2008)\\[0pt] [2] K. Singh et al., Phys. Rev. B 84, 064129 (2011)\\[0pt] [3] N. Kojima et al., J. Phys. Soc. Jpn. 62, 4137 (1993)

–

Authors

  • Michael Schmidt

    • Experimental Physics V, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, D-86135 Augsburg, Germany

  • Zhe Wang

    • Experimental Physics V, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, D-86135 Augsburg, Germany

  • F. Mayr

    • Experimental Physics V, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, D-86135 Augsburg, Germany

  • S. Toth

    • Helmholtz-Zentrum Berlin fuer Materialien und Energie, D-14109 Berlin, Germany

  • B. Lake

    • Helmholtz-Zentrum Berlin fuer Materialien und Energie, D-14109 Berlin, Germany

  • A.T.M.N. Islam

    • Helmholtz-Zentrum Berlin fuer Materialien und Energie, D-14109 Berlin, Germany

  • V. Tsurkan

    • Experimental Physics V, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, D-86135 Augsburg, Germany

  • A. Loidl

    • Experimental Physics V, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, D-86135 Augsburg, Germany

  • J. Deisenhofer

    • Experimental Physics V, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, D-86135 Augsburg, Germany