Metamaterials offer the prospect of new science and applications. They have been designed by shaping or changing the material of the individual meta-molecules to achieve properties not naturally attainable. Composite meta-molecules incorporating a magnetic component offer new opportunities. In this work we report on the interaction between a non-magnetic split ring resonator (SRR) and a thin film of yttrium iron garnet (YIG). Strong hybridized resonances are observed. While the SRR is characterized by a magnetic and electric resonance, in practice, it is found that the YIG couples strongly to this symmetric (electric) mode of the SRR. It is also demonstrated that the anti-crossing region provides fertile ground for the creation of elementary excitations such as backward volume magnetostatic waves.

By coupling magnetic elements to metamaterials, new hybrid metamolecules can be created with interesting properties such as photo-magnon coupling. Here, we present results for a hybrid metamolecule, using a hard as opposed to soft magnetic material. This was achieved by placing a thin film of single crystal hard FeCo in close proximity to a split ring resonator (SRR). To suppress eddy-current shielding the FeCo film was patterned into 100 µm disks. The resulting metamolecule exhibits photon-magnon coupling when the FeCo is on resonance (FMR). Three new features are demonstrated and discussed. One, hard magnets allow FMR to be performed in near zero field, thereby partially eliminating the need for applied fields. Two, because the FMR is anisotropic, angular control over hybrid SRR/FMR resonances is achieved. Three, the single crystal FeCo can be re-magnetized parallel/perpendicular to the plane of the SRR, in real time, thus opening the door to magnetically configurable metamaterials. Finally, the work was performed using coplanar waveguide (CPW) excitation. A study was made therefore of how best to excite the numerous transverse magnetic (TM) and transverse electric (TE) modes of the SRR, using near-field CPWexcitation. Such detail is important, if the strongest signals are to be achieved. Photon-magnon coupling strengths of up to 5% are demonstrated.

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We report on a metamolecule antenna, based on a fish-scale design but augmented with two split-ring resonators (SRRs) placed within the fish-scale loops. The properties of the antenna resonator, with and without additional SRRs, were examined using finite element method simulations (COMSOL Multiphysics). The simulation findings were subsequently confirmed experimentally, using a vector network analyser coupled to an antenna-loaded coplanar waveguide (CPW). The addition of SRRs to the fish-scale meta-molecule leads to a demonstrably large increase in microwave-absorption. It is shown that the fish-scale/SRR/CPW combination performs as a microwave antenna. Simulations of the antenna gain and far-field emission are presented and discussed.

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