The magnetic response of graphene split-ring metamaterials

Graphene has emerged as a promising platform for THz plasmonics, allowing high confinement, long lifetimes and fast electrical tunability. Here, we predict a strong magnetic dipole response by graphene split nanorings at THz frequencies, allowing the attainment of metamaterials with a high degree of field confinement (approximately one hundredth of the excitation wavelength) that is not reachable with conventional noble metals. The magnetic response of highly doped graphene split-rings in the far-infrared is much stronger than that displayed by gold structures of similar thicknesses. We further explored stacked graphene layers as a practical way of producing high-frequency magnetism in thin, electrically tunable metamaterials. Our results support the great potential of using graphene to achieve electrically tunable magnetic metamaterials.