Waves in the unseen : theory of spin excitations in a quantum spin nematic
Abstract
The idea that a quantum magnet could act like a liquid crystal, breaking spin-rotation symmetry without breaking time-reversal symmetry, holds an abiding fascination. However, the very fact that spin nematic states do not break time-reversal symmetry renders them "invisible" to the most common probes of magnetism - they do not exhibit magnetic Bragg peaks, a static splitting of lines in NMR spectra, or oscillations in muSR. Nonetheless, as a consequence of breaking spin-rotation symmetry, spin-nematic states do possess a characteristic spectrum of dispersing excitations which could be observed in experiment. With this in mind, we develop a symmetry-based description of long-wavelength excitations in a spin-nematic state, based on an SU(3) generalisation of the quantum non-linear sigma model. We use this field theory to make explicit predictions for inelastic neutron scattering, and argue that the wave-like excitations it predicts could be used to identify the symmetries broken by the otherwise unseen spin-nematic order.
Keywords
Cite
@article{arxiv.1307.5131,
title = {Waves in the unseen : theory of spin excitations in a quantum spin nematic},
author = {Andrew Smerald and Nic Shannon},
journal= {arXiv preprint arXiv:1307.5131},
year = {2013}
}
Comments
Accepted for publication in Physical Review B, 23 pages, 13 figures, 2 animations attached as ancillary files