Giant Magneto-Optical Kerr Enhancement from Films on SiC Due to the Optical Properties of the Substrate
Journal Article - Open Access
NAVAL RESEARCH LAB WASHINGTON DC WASHINGTON United States
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We report a giant enhancement of the mid-infrared MIR magneto-optical complex Kerr angle polarization change of reflected light in a variety of materials grown on SiC. In epitaxially-grown multilayer graphene, the Kerr angle is enhanced by a factor of 68, which is in good agreement with Kerr signal modeling. Strong Kerr enhancement is also observed in Fe films grown on SiC and Al-doped bulk SiC. Our experiments and modeling indicate that the enhancement occurs at the high-energy edge of the SiC reststrahlen band where the real component of the complex refractive index n over tilde passes through unity. Furthermore, since the signal is greatly enhanced when n over tilde 1, the enhancement is predicted to exist over the entire visible and IR spectrum for a free-standing film. We also predict similar giant enhancement in both Faraday transmission and Kerr rotation for thin films on a metamaterial substrate with refractive index n over tilde -1. This paper demonstrates that the substrate used in magneto-optical Kerr effect MOKE measurements must be carefully chosen when investigating magneto-optical materials with weak MOKE signals or when designing MOKE-based optoelectronic devices.