We report the experimental observation of dielectric relaxation by quantum critical magnons. Complex capacitance measurements reveal a dissipative feature with a temperature-dependent amplitude due to low-energy lattice excitations and an activation behavior of the relaxation time. The activation energy softens close to a field-tuned magnetic quantum critical point at H=Hc and follows single-magnon energy for H>Hc, showing its magnetic origin. Our study demonstrates the electrical activity of coupled low-energy spin and lattice excitations, an example of quantum multiferroic behavior.
@article{arxiv.2302.04234,
title = {Dielectric relaxation by quantum critical magnons},
author = {Daniel Flavián and Pavel A. Volkov and Shohei Hayashida and Kirill Yu. Povarov and Severian Gvasaliya and Premala Chandra and Andrey Zheludev},
journal= {arXiv preprint arXiv:2302.04234},
year = {2023}
}