Giant Faraday rotation of excitons in 2D semiconductor monolayers

Abstract: In this talk, first I will discuss a new technique which we have developed to perform Faraday Rotation spectroscopy at micron scales on 2D materials [1]. This technique enhances the spectral acquisition times by 2 to 3 orders of magnitude, compared to the state-of-the-art modulation spectroscopy methods. By performing Faraday rotation spectroscopy measurements on hBN-encapsulated monolayers of WSe2 and MoSe2 under out-of-plane applied magnetic fields up to B=1.4 T, we demonstrate that the plane of polarization of light shows a giant Faraday rotation of many degrees in moderate magnetic fields around the excitonic transitions [2]. This results in a ultrahigh Verdet constant (>3 x 10^7 rad/T/m) at the exciton resonance. Such giant Faraday rotation appears due to a combination of large excitonic oscillator strengths and high exciton g-factors in semiconducting transition metal dichalcogenides. Our work opens pathways to ultrathin magneto-optical technologies in the visible and infrared regions, such as optical isolators.
References:
[1] Carey et al., Small Methods, DOI: 10.1002/smtd.202200885 (2022)
[2] Carey et al., under review (2022)