Spin dynamics of the triangular lattice antiferromagnet ${\alpha}$-SrCr$_2$O$_4$

ORAL

Abstract

We study the spin dynamics of the layered $S=3/2$ triangular lattice antiferromagnet ${\alpha}$-SrCr$_2$O$_4$ by means of inelastic neutron scattering on powder and single-crystal specimen. While the incommensurate long-range order observed below $T_{\rm N}$=43K resembles the usual 120$^\circ$-structure predicted for the perfect triangular lattice antiferromagnet, a spin-wave theory fit to the entire single-crystal dataset reveals strongly distorted exchange interactions. The extreme sensitivity of direct-exchange interactions to the small static Cr$^{3+}$-Cr$^{3+}$ distance variations reported by neutron diffraction, is quantitatively confirmed by {\it ab-initio} calculations that corroborate the spin-wave theory results.

*This research was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-FG02-08ER46544

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Authors

  • M. Mourigal

    • Johns Hopkins

  • J.-J. Wen

    • Johns Hopkins

  • Y. Wan

    • Johns Hopkins

  • S. Koohpayeh

    • Johns Hopkins

  • R. Vald\'es Aguilar

    • Johns Hopkins

  • N.P. Armitage

    • Johns Hopkins

  • O. Tchernyshov

    • Johns Hopkins

  • C.L. Broholm

    • Johns Hopkins

  • S. Dutton

    • Princeton

  • R.J. Cava

    • Princeton

  • T. Birol

    • Cornell

  • H. Das

    • Cornell

  • C.J. Fennie

    • Cornell

  • L. Lin

    • Nanjing University

  • J.-M. Liu

    • Nanjing University

  • M.B. Stone

    • Oak Ridge National Laboratory

  • W. Tian

    • Oak Ridge National Laboratory