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arXiv · 1707.03503

THz-frequency cavity magnon-phonon-polaritons in the strong coupling regime

Prasahnt Sivarajah·Andreas Steinbacher·Blake Dastrup·Keith Nelson
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Abstract

We demonstrate the strong coupling of both magnons and phonons to terahertz (THz) frequency electromagnetic (EM) waves confined to a photonic crystal (PhC) cavity. Our cavity consists of a two-dimensional array of air-holes cut into a hybrid slab of ferroelectric lithium niobate (LiNbO$_3$) and erbium orthoferrite (ErFeO$_3$), a canted antiferromagnetic crystal. The phonons in LiNbO$_3$ and the magnons in ErFeO$_3$ are strongly coupled to the electric and magnetic field components of the confined EM wave, respectively. This leads to the formation of new cavity magnon-phonon-polariton modes, which we experimentally observe as a normal-mode splitting in the frequency spectrum and an avoided crossing in the temperature-frequency plot. The cavity also has a mode volume of $V=3.4\times10^{-3}λ^3\simeq0.5(λ/n)^3$ $μ$m$^3$ and can achieve a Q-factor as high as 1000. These factors facilitate the pursuit of the fields of THz cavity spintronics and quantum electrodynamics.

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Prasahnt Sivarajah, Andreas Steinbacher, Blake Dastrup, Keith Nelson. 2017-07-12. THz-frequency cavity magnon-phonon-polaritons in the strong coupling regime. https://arxiv.org/abs/1707.03503

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