Enhancement and regulation of magneto-optic effects

What is it about?

In this article, we theoretically study the Kerr effects excited by the TM- or TE-polarized wave illuminating on a bulk WSM. A 4×4 magneto-optical matrix is revealed for obtaining the calculation of Kerr angles by utilizing Maxwell’s equations and boundary conditions. It is shown that the large absolute Kerr anglesp and s of nearly 21° are maintained due to the situation that the cross-polarized reflection coefficients |rps| and |rsp| are greater than but close to the co-polarized reflection coefficients |rpp| and |rss|. What is more important, the enhanced Kerr angles with their absolute values of 45° can be acquired at two different frequencies due to the sharp increases of |rpp| and |rss| based on ENZ response. Notably, the ENZ frequency of WSM can be adjusted by altering the Fermi energy and tilt degree, thus the enhanced Kerr angles can be obtained at different frequencies. Additionally, it is found that the incident angle should be declined with the increase of thickness of WSM to enable the enhancement of Kerr angle s. Finally, the effects of Weyl node separation on Kerr angles are examined. We firmly believe our study may find practical applications in optical Kerr devices.

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Why is it important?

A 4×4 magneto-optical matrix is revealed to study the Kerr effects induced by the TM- or TE-polarized wave illuminating on a bulk WSM. Results show that the Kerr angles maintain large absolute values of 21°, which is caused by the close cross- and co-polarized reflection coefficients. The Kerr angles can be further enhanced at frequencies close to the ENZ frequency, where the maximum absolute Kerr angles of 45° have been received due to the sharp increases of co-polarized reflection coefficients. Remarkably, the tunable ENZ frequency of WSM enables the tunable enhanced Kerr angles at different frequencies.

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