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

## TL;DR

This paper demonstrates a significant enhancement of the magneto-optical Kerr effect in films on SiC substrates due to the substrate's optical properties, enabling improved detection and device design in the infrared spectrum.

## Contribution

It reveals that SiC substrates can dramatically amplify Kerr signals at specific energies, and predicts similar effects with other substrates and in different spectral ranges.

## Key findings

- Kerr angle enhanced by a factor of 68 in multilayer graphene on SiC
- Enhancement occurs at the high-energy edge of SiC's reststrahlen band
- Predicted giant Kerr and Faraday effects on metamaterial substrates with n=-1

## Abstract

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 modelling 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 passes through unity. Furthermore, since the signal is greatly enhanced when n=1, the enhancement is predicted to exist over the entire visible/infrared (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=-1. This work demonstrates that the substrate used in MOKE measurements must be carefully chosen when investigating magneto-optical materials with weak MOKE signals or when designing MOKE-based optoelectronic devices.

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Source: https://tomesphere.com/paper/1901.06536