Volume 80, Number 6, December 2007
|Number of page(s)||6|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||08 November 2007|
Spin-wave spectra of a Kagome stripe
Max-Planck-Institut für Physik Komplexer Systeme - D-01187 Dresden, Germany
2 Department of Physics, University of Wisconsin - Madison, WI 53706, USA
Accepted: 17 October 2007
We study ground-state degeneracy and spin-wave excitations in a 1D version of a Kagome antiferromagnet —a Heisenberg antiferromagnet on a Kagome stripe. We show that for nearest-neighbor interaction, the classical ground state is infinitely degenerate. For any spin configuration from the degenerate set, the classical spin-wave spectrum contains, in addition to Goldstone modes, a branch of zero-energy excitations, and a zero mode in another branch. We demonstrate that the interactions beyond nearest neighbors lift the degeneracy, eliminate a zero mode, and give a finite dispersion to formerly zero-energy branch, leaving only Goldstone modes as zero-energy excitations.
PACS: 75.10.Pq – Spin chain models / 75.30.Ds – Spin waves
© EPLA, 2007
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