Low-lying magnetic excitations in the distorted triangular lattice antiferromagnet $\alpha$-CaCr$_2$O$_4$

ORAL

Abstract

We will discuss our results on $\alpha$-CaCr$_2$O$_4$ obtained by FIR and Terahertz spectroscopy. This compound orders below $T_{\mathrm{N}}$ = 42.6 K in a proper screw 120$^\circ$ magnetic order, but shows additional low-lying magnetic modes indicative for the vicinity of a more complex magnetic order [1-2]. Our spectra obtained by FTIR and THz-TD spectroscopy show several optical magnons appearing below the magnetic ordering with anomalous temperature dependence. We will discuss their polarization dependence and a possible magnetoelastic coupling of these modes.\\[4pt] [1] S. Toth et al., Phys. Rev. B 84, 054452 (2011)\\[0pt] [2] S. Toth et al., PRL 109, 127203 (2012)

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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

  • 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

  • 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