Neutron scattering study of the dimerized spin 1/2 AFM kagome lattice in $Rb_2Cu_3SnF_{12}$

ORAL

Abstract

The deformed AFM kagome lattice $Rb_2Cu_3SnF_{12}$ is the first realization of 'pinwheel' valence bond solid (VBS) ground state system [1]. Using inelastic neutron scattering technique, we mapped out the spin excitation spectrum up to 12 meV. The singlet to triplet transition is split by a substantial Dzyaloshinskii-Moriya (DM) interaction, with the energy gap at 2.4 meV ($S_z$= $\pm$ 1) and 6.9 meV ($S_z$ = 0), respectively. While both excitations are non-dispersive to within 1.0 meV for wave vectors, $q_z$, perpendicular to the kagome like plane, the intensity varies differently with $q_z$ for the two modes. This difference can be explained by the different polarization factor for $S_z$= $\pm$ 1 and $S_z$ = 0 excitations. Under a magnetic field along the c-axis, the low energy gap persist near 1 meV for the fields between 9 T and 15 T. Our findings emphasize the important role of DM interaction in this material.\\[4pt] [1] K. Matan, T. Ono, Y. Fukumoto, T. J. Sato, J. Yamaura, M. Yano, K. Morita, and H. Tanaka, Nature Physics 10 (2010).

–

Authors

  • Yang Zhao

    • University of Maryland, College Park / NIST NCNR
    • NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899

  • K. Matan

    • Mahidol University, Thailand

  • Y. Nambu

    • Tohoku University, Japan

  • T. J. Sato

    • Tohoku University, Japan

  • Y. Fukumoto

    • Tokyo University of Science, Japan

  • T. Ono

    • Osaka Prefecture University, Japan

  • H. Tanaka

    • Tokyo Institute of Technology, Japan

  • Collin Broholm

    • Johns Hopkins University / NIST NCNR
    • Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University
    • IQM, JHU; NCNR, NIST; Neutron Science Directorate, ORNL
    • Department of Physics and Astronomy, Johns Hopkins University, Baltimore 21218 MD USA
    • Johns Hopkins University
    • Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA

  • A. Podlesnyak

    • SNS

  • G. Ehlers

    • SNS