Normal Modes of a Spin Cycloid or Helix

ORAL

Abstract

Although spin cycloids and helices are quite common, remarkably little is known about the normal modes of a spin cycloid or helix with finite length on a discrete lattice. Based on simple one-dimensional lattice models, we numerically evaluate the normal modes of a spin cycloid or helix produced by either Dzyalloshinskii-Moriya (DM) or competing exchange (CE) interactions. The normal modes depend on the type of interaction and on whether the nearest-neighbor exchange is antiferromagnetic (AF) or ferromagnetic (FM). In the AF/DM and FM/DM cases, there is only a single Goldstone mode; in the AF/CE and FM/CE cases, there are three. For FM exchange, the spin oscillations produced by non-Goldstone modes contain a mixture of tangential and transverse components. For the DM cases, we compare our numerical results with analytic results in the continuum limit.

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Presenters

  • Randy Fishman

    Oak Ridge National Laboratory, Materials Science and Technology Division, Oak Ridge National Lab, Oak Ridge, Tennessee, USA

Authors

  • Randy Fishman

    Oak Ridge National Laboratory, Materials Science and Technology Division, Oak Ridge National Lab, Oak Ridge, Tennessee, USA

  • Toomas Room

    National Institute of Chemical Physics and Biophysics, Estonia

  • Rogério de Sousa

    Dept. of Physics and Astronomy, University of Victoria, BC, Canada, Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia, Canada, Department of Physics and Astronomy, University of Victoria, Canada, Department of Physics and Astronomy, University of Victoria, BC, Canada