Heterogeneity in Dynamic Metamolecules

Here, we fabricated spherical assemblies of metal nanobeads with size or material heterogeneity to study how the mismatch in the strength and energy of surface plasmon resonance (SPR) of nanobead building blocks affects the global magnetic resonance modes. In binary metamolecules (BMMs) composed of 15 and 45 nm Au beads, small 15 nm beads can act as the medium between sparsely placed large nanobeads and enhance the overall plasmon coupling, resulting in a strong and narrow magnetic dipole resonance. In BMMs made of Au and Ag nanobeads of the same size, the coupling between Au and Ag nanobeads significantly contributes to the magnetic resonance modes, affecting both their strength and position, while it does not significantly affect electric modes. These results provide valuable guidelines for the fabrication of colloidal metamolecules with desired metamaterial properties.