Spontaneous magnon decays in planar ferromagnet
Institute of Physics, Opole University - Opole, 45-052, Poland
2 Service de Physique Statistique, Magnétisme et Supraconductivité, UMR-E9001 CEA-INAC/UJF 17 rue des Martyrs, F-38054 Grenoble cedex 9, France
3 Max-Planck-Institut für Physik Komplexer Systeme - Nöthnitzer str. 38, D-01187 Dresden, Germany
Accepted: 15 May 2011
We predict that spin-waves in an easy-plane ferromagnet have a finite lifetime at zero temperature due to spontaneous decays. In zero field the damping is determined by three-magnon decay processes, whereas decays in the two-particle channel dominate in a transverse magnetic field. Explicit calculations of the magnon damping are performed in the framework of the spin-wave theory for the XXZ square-lattice ferromagnet with an anisotropy parameter λ<1. In zero magnetic field the decays occur for λ*<λ<1 with λ*≈1/7. We also discuss the possibility of experimental observation of the predicted effect in a number of ferromagnetic insulators.
PACS: 75.30.Ds – Spin waves / 75.10.Jm – Quantized spin models, including quantum spin frustration / 75.50.Dd – Nonmetallic ferromagnetic materials
© EPLA, 2011