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.

*Research by RF sponsored by the U.S. Department of Energy, Office of Basic Energy Sciences, Materials Sciences and Engineering Division. TR would like to acknowledge support from the Estonian Ministry of Education and Research with institutional research funding IUT23-3, and the European Regional Development Fund Project No. TK134. RdS acknowledges support from NSERC (Canada) through its Discovery program (RGPIN-2015-03938).

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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