Switching the electric and magnetic responses in a metamaterial

We demonstrate in this Rapid Communication that in an assembly of stacked metallic U-shaped resonators, pure magnetic and electric responses are, respectively, realized, and the magnetic and electric responses can be switched at the same frequency by changing the polarization of incident light for 90 degrees. This unique feature originates from the topological symmetry of the structure. We suggest that this property opens a gateway to construct metamaterial with tunable permittivity and permeability.