Effect of metal thickness on magnetic resonance and left-handed behavior for normal incidence of the electromagnetic wave

We investigate by using simulation the magnetic resonance and left-handed behavior of hexagonal-ring pairs with various metal thicknesses in the infrared and visible bands, respectively, for normal incidence of the electromagnetic wave. The transmission spectra of hexagonal-ring pairs with various metal thicknesses show that negative permeability or left-handed behavior of hexagonal-ring pairs occurs only when the metal thickness is larger than a critical value, and the intensity of magnetic resonance or left-handed behavior increases with the increment of metal thickness. Based on the bianisotropic medium model, we numerically calculate the electromagnetic parameters and confirm the negative permeability or left-handed behavior of a hexagonal-ring pairs. In the case of normal incidence, the magnetic resonance of a hexagonal-ring pair with only one metal layer arises from the anti-symmetric current distribution around the gap of the hexagonal-ring pair.