  Dynamic metamolecules (DMMs) are composed of a dielectric core made of
hydrogel surrounded by randomly-packed plasmonic beads that can display
magnetic resonances when excited by light at optical frequencies. Their optical
properties can be controlled by controlling their core diameter through
temperature variations. We have recently shown that DMMs display strong optical
magnetism, including magnetic dipole and magnetic quadrupole resonances,
offering significant potential for novel applications. Here, we use a T-matrix
approach to characterize the magnetic multipole resonance modes of model
metamolecules and explore their presence in experimental data. We show that
high-order multipole resonances become prominent as the bead size and the
overall structure sizes are increased, and when the the inter-bead gap is
decreased. In this limit, mode mixing among high-order magnetic multipole modes
also become significant, particularly in the directional scattering spectra. We
discuss trends in magnetic scattering observed in both experiments and
simulations, and provide suggestions for experimental design and verification
of high-order optical magnetic resonances in the forward or backward scattering
spectra. In addition, angular scattering of higher-order magnetic modes can
display Fano-like interference patterns that should be experimentally
detectable.
