Focused-ion-beam nanofabrication of near-infrared magnetic metamaterials

Split-ring resonators with a magnetic resonance in the near-infrared have been fabricated using the rapid-prototyping capabilities of focused-ion-beam writing. By varying the design parameters, a continuous transition from a degenerate Mie resonance to a magnetic-dipole response is shown (see Figure). In particular, a negative magnetic permeability at a wavelength of 2.4 mu m and a negative magnetic susceptibility at a wavelength of 1.7 mu m are demonstrated.