Surface polaritons born by inter-element coupling in magnetic metamaterials

We studied theoretically electromagnetic surface waves that propagate along an interface between air and magnetic metamaterials. The metamaterials comprise coupled split-ring resonators. We found two types of waves. Waves of the first type propagate due to interaction of the electromagnetic wave with individual rings, which leads to negative magnetic permeability. They are analogous to the well-known surface plasmons. Waves of the second type, however, are of a different nature and propagate when near-field coupling between the rings exists in the transverse direction. Interaction between the two types leads to complex dispersion characteristics, whose properties can be tailored by changing the inter-element coupling.