Magnon breakdown in a two dimensional triangular lattice heisenberg antiferromagnet of multiferroic LuMnO3

Joosung Oh, Manh Duc Le, Jaehong Jeong, Jung Hyun Lee, Hyungje Woo, Wan Young Song, T. G. Perring, W. J.L. Buyers, S. W. Cheong, Je Geun Park

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Abstract

The breakdown of magnons, the quasiparticles of magnetic systems, has rarely been seen. By using an inelastic neutron scattering technique, we report the observation of spontaneous magnon decay in multiferroic LuMnO3, a simple two dimensional Heisenberg triangular lattice antiferromagnet, with large spin S=2. The origin of this rare phenomenon lies in the nonvanishing cubic interaction between magnons in the spin Hamiltonian arising from the noncollinear 120 spin structure. We observed all three key features of the nonlinear effects as theoretically predicted: a rotonlike minimum, a flat mode, and a linewidth broadening, in our inelastic neutron scattering measurements of single crystal LuMnO3. Our results show that quasiparticles in a system hitherto thought of as "classical" can indeed break down.

Original languageEnglish (US)
Article number257202
JournalPhysical review letters
Volume111
Issue number25
DOIs
StatePublished - Dec 18 2013

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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