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Anomalous spin excitation spectra in honeycomb systems Na<sub>2+x</sub>M<sub>2</sub>TeO<sub>6</sub> (M=Co and Ni) with zig-zag magnetic ordering

ORAL

Abstract

The role played by the magnetic frustration arising from competing exchange interactions on the magnetic properties of honeycomb systems continues to be the subject of intense research. Competition between first, second and third neighbor exchange interactions results in rich magnetic phase diagrams that include Néel, zigzag, stripy, and spiral orders. Anisotropic exchange interactions that arise from spin-orbit coupling can lead to various exotic quantum-disordered states. Here we discuss the results of neutron scattering measurements performed on the honeycomb systems Na2+xM2TeO6 (M=Co and Ni). The diffusive Na atoms provide an effective control of the interlayer magnetic couplings, and therefore a route for tuning the lattice dimensionality. The changes in the static magnetic order and spin-dynamics for samples with different Na content are discussed. We also show that spin-wave excitation spectra obtained from stoichiometric powder samples cannot be well described using a simple isotropic Heisenberg spin Hamiltonian. An alternative model with anisotropic exchange coupling is evaluated and discussed.

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Presenters

  • Vasile Garlea

    Oak Ridge National Laboratory, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, Oak Ridge National Lab, Neutron Scattering Division, Oak Ridge National Laboratory

Authors

  • Vasile Garlea

    Oak Ridge National Laboratory, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, Oak Ridge National Lab, Neutron Scattering Division, Oak Ridge National Laboratory

  • Anjana Samarakoon

    Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, Oak Ridge National Lab

  • Qiang Chen

    Dep. Physics and Astronomy, University of Tennessee, Knoxville TN, University of Tennessee, Department of Physics and Astronomy, University of Tennessee

  • Haidong Zhou

    Dep. Physics and Astronomy, University of Tennessee, Knoxville TN, Department of Physics and Astronomy, University of Tennessee, Knoxville, University of Tenessee, University of Tennessee, Knoxville, Physics and Astronomy, University of Tennessee at Knoxville, University of Tennessee, Department of Physics and Astronomy, University of Tennessee