Giant magneto-optical Kerr enhancement from films on SiC due to the optical properties of the substrate

• Published in: Physical review. B 2019-02, Vol.99 (8), p.085440, Article 085440
• Main Authors: Mukherjee, A., Ellis, C. T., Arik, M. M., Taheri, P., Oliverio, E., Fowler, P., Tischler, J. G., Liu, Y., Glaser, E. R., Myers-Ward, R. L., Tedesco, J. L., Eddy, C. R., Gaskill, D. Kurt, Zeng, H., Wang, G., Cerne, J.
• Format: Article
• Language: English
• Subjects: Epitaxial growth; Graphene; Kerr magnetooptical effect; Mathematical models; Metamaterials; Modelling; Multilayers; Optical materials; Optical properties; Optics; Optoelectronic devices; Refractivity; Substrates; Thin films
• ISSN: 2469-9950; 2469-9969
• DOI: 10.1103/PhysRevB.99.085440

We report a giant enhancement of the midinfrared 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 ñ passes through unity. Furthermore, since the signal is greatly enhanced when ñ=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 ñ=−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.