Anomalously large damping of long-wavelength quasiparticles caused by long-range interaction

Abstract

We demonstrate that long-range interaction in a system can lead to a very strong interaction between long-wavelength quasiparticles and make them heavily damped. In particular, we discuss magnon spectrum using 1/S expansion in 3D Heisenberg ferromagnet (FM) with arbitrary small dipolar forces at T<<T_C. We obtain that a fraction of long-wavelength magnons with energies e_k<T has anomalously large damping G_k (ratio G_k/e_k reaches 0.3 for certain k). This effect is observed both in quantum and classical FMs. Remarkably, this result contradicts expectation of the quasiparticle concept according which a weakly excited state of a many-body system can be represented as a collection of weakly interacting elementary excitations. Particular materials are pointed out which are suitable for corresponding experiments.

13 pages, 6 figures, some minor corrections have been made, to appear in PRB

References in corpus (3)

• Decay of quasiparticles in quantum spin liquids
• Renormalization of the spin-wave spectrum in three-dimentional ferromagnets with dipolar interaction
• Spin-wave interaction in two-dimensional ferromagnets with dipolar forces

Cited by in corpus (4)

• "Quasi-particle breakdown" in the quasi-one-dimensional Ising ferromagnet CoNb${}_2$O${}_6$
• Field-dependence of magnon decay in yttrium iron garnet thin films
• Role of dimensionality in spontaneous magnon decay: easy-plane ferromagnet
• Anomalous spin waves in CsFeCl${}_3$ and RbFeCl${}_3$