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.

arXiv comment13 pages, 6 figures, some minor corrections have been made, to appear in PRB

References in corpus (7)

• Dynamics of composite Haldane spin chains in IPA-CuCl3
• Quasiparticle breakdown in a quantum spin liquid
• Instability of Magnons in Two-dimensional Antiferromagnet at High Magnetic Fields
• Decay of quasiparticles in quantum spin liquids
• Magnon decay in gapped quantum spin systems
• 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 (8)

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• Low Temperature Dynamics of Magnons in a Spin-1/2 Ladder Compound
• Field-dependence of magnon decay in yttrium iron garnet thin films
• Order-by-disorder effects in antiferromagnets on face-centered cubic lattice
• Breakdown of long-wavelength magnons in cubic antiferromagnets with dipolar forces at small temperature
• Anomalous spin waves in CsFeCl${}_3$ and RbFeCl${}_3$
• Collisionless kinetic theory for parametrically pumped magnons
• Role of dimensionality in spontaneous magnon decay: easy-plane ferromagnet