Magnetic Surface Polariton in a Planar Biaxial Metamaterial with Dual Negative Magnetic Permeabilities

The magnetic surface polaritons (MSPs) mode rarely exists in natural materials, mainly due to their limited magnetic response. In order to understand the relationship between the MSPs mode and the limited magnetic response, we theoretically derive a general dispersion equation of the MSPs mode for two kinds of biaxial anisotropic media. The dispersion equation suggests the requirements of μ _x < 0 < ε _z, μ _xμ _y > 1, and momentum conservation need to be satisfied, which guides us to design a planar biaxial magnetic metamaterials (PBMM) with two orthogonal negative permeabilities (i. e., μ _x < 0 and μ _y < 0). In addition, the results of the retrieval magnetic permeability and electric permittivity indeed point out that our PBMM satisfies the aforementioned requirements. Meanwhile, we investigate the mechanism of the magnetic field by a consideration of an induced current loop, and subsequently we demonstrate the artificial MSPs mode under transverse electric excitation by numerical simulation. After a numerical fit of simulation results, we find that the field of the MSPs mode is in good agreement with the analytical calculation of Maxwell's equations. Moreover, we also simulate three unsatisfied aforementioned requirements as control conditions to verify the general dispersion equation of the MSPs mode.