Abstract
Numerical solutions of coupled Maxwell and Landau-Lifshitz-Gilbert equations for a magnetized yttrium iron garnet (YIG) sphere acting as a one-stage filter are presented. The filter is analysed using finite-difference time-domain technique. Contrary to the state of the art, the study shows that the maximum electromagnetic power transmission through the YIG filter occurs at the frequency of the magnetic plasmon resonance with the effective permeability of the gyromagnetic medium μr ≈ −2, and not at a ferromagnetic resonance frequency. Such a new understanding of the YIG filter operation, makes it one of the most commonly used single-negative plasmonic metamaterials. The frequency of maximum transmission is also found to weakly depend on the size of the YIG sphere. An analytic electromagnetic analysis of resonances in a YIG sphere is performed for circularly polarized electromagnetic fields. The YIG sphere is situated in a free space and in a large spherical cavity. The study demonstrates that both volume resonances and magnetic plasmon resonances can be solutions of the same transcendental equations.
Highlights
Numerical solutions of coupled Maxwell and Landau-Lifshitz-Gilbert equations for a magnetized yttrium iron garnet (YIG) sphere acting as a one-stage filter are presented
Does the maximum transmittance of the filter occur at the ferromagnetic resonance frequency, f = fres, where magnetic losses of YIG are the largest? Is the magnetic field uniform in the YIG sample at the frequency of maximum transmittance as predicted by magneto-quasistatic models5,6? How is the maximum transmittance of the filter related to the permeability of the YIG sphere? The goal of this work is to investigate these questions using a rigorous electromagnetic analysis
We first numerically analysed a one-stage spherical YIG filter using the finite-difference time-domain (FDTD) method implemented in the QuickWave 3D (QW-3D) simulator[23]
Summary
Jerzy Krupka[1], Bartlomiej Salski[2], Pawel Kopyt2 & Wojciech Gwarek[2] received: 11 July 2016 accepted: 19 September 2016. Contrary to the state of the art, the study shows that the maximum electromagnetic power transmission through the YIG filter occurs at the frequency of the magnetic plasmon resonance with the effective permeability of the gyromagnetic medium μr ≈ −2, and not at a ferromagnetic resonance frequency. Such a new understanding of the YIG filter operation, makes it one of the most commonly used single-negative plasmonic metamaterials. We first numerically analysed a one-stage spherical YIG filter using the finite-difference time-domain (FDTD) method implemented in the QuickWave 3D (QW-3D) simulator[23] This simulation uses the gyrotropic permeability tensor, as in Eqs (1–4)[24]. We analysed a rigorous electromagnetic model of the resonances in gyromagnetic spheres situated in a free space and in spherical metal cavities
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