Zero-magnon sound in quantum Heisenberg ferromagnets

Abstract

Using a functional renormalization group approach we show that at low temperatures and in a certain range of magnetic fields the longitudinal dynamic structure factor of quantum Heisenberg ferromagnets in dimensions $D\le 2$ exhibits a well-defined quasi-particle peak with linear dispersion that we identify as zero-magnon sound. In $D>2$ the larger phase space available for the decay into transverse spin waves leads only to a broad hump centered at zero frequency whose width scales linearly in momentum.

6 pages, 3 figures

References in corpus (1)

• From local to critical fluctuations in lattice models: a non-perturbative renormalization-group approach

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