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arXiv · 2106.09447

Anomalous spin waves in CsFeCl$_{3}$ and RbFeCl$_{3}$

L. Stoppel·S. Hayashida·Z. Yan·A. Podlesnyak·A. Zheludev
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Abstract

We investigate magnetic excitations in the $S=1$ easy-plan-type triangular antiferromagnets CsFeCl$_{3}$ and RbFeCl$_{3}$ through a combination of inelastic neutron scattering measurements and spin-wave theory calculations based on an established exchange-coupling Hamiltonian. We show that in either material the model falls short of providing an adequate description of the measured intensities and for RbFeCl$_{3}$ even fails to reproduce the measured dispersion relation. The most striking discrepancy is a very anisotropic azimuthal intensity distribution in the acoustic spin-wave branches in the long-wavelength limit, which is incompatible with spin-wave theory on a fundamental level. The observed anomalies are attributed to long-range dipolar interactions.

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L. Stoppel, S. Hayashida, Z. Yan, A. Podlesnyak, A. Zheludev. 2021-06-17. Anomalous spin waves in CsFeCl$_{3}$ and RbFeCl$_{3}$. https://doi.org/10.1103/physrevb.104.094422

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