High-performance broadband Faraday rotation spectroscopy of 2D materials and thin magnetic films

Abstract

We present a Faraday rotation spectroscopy (FRS) technique for measurements on the micron scale. Spectral acquisition speeds of many orders of magnitude faster than state-of-the-art modulation spectroscopy setups are demonstrated. The experimental method is based on charge-coupled-device detection, avoiding speed-limiting components, such as polarization modulators with lock-in amplifiers. At the same time, FRS spectra are obtained with a sensitivity of 20 $\mu$rad (0.001${}^{\circ }$) over a broad spectral range (525 nm - 800 nm), which is on par with state-of-the-art polarization-modulation techniques. The new measurement technique also automatically cancels unwanted Faraday rotation backgrounds. Using the setup, we perform Faraday rotation spectroscopy of excitons in a hBN-encapsulated atomically thin semiconductor WS${}_2$ under magnetic fields of up to 1.4 T at room temperature and liquid helium temperature. We determine the A exciton g-factor of -4.4 $\pm$ 0.3 at room temperature, and -4.2 $\pm$ 0.2 at liquid helium temperature. In addition, we perform FRS and hysteresis loop measurements on a 20 nm thick film of an amorphous magnetic Tb${}_{0.2}$Fe${}_{0.8}$ alloy.

8 pages, 4 figures

References in corpus (7)

• Magnetic 2D materials and heterostructures
• Measurement of the optical dielectric function of transition metal dichalcogenide monolayers: MoS2, MoSe2, WS2 and WSe2
• Magneto-optics in transition metal diselenide monolayers
• Excitonic valley effects in monolayer WS${}_2$ under high magnetic fields
• Magnetooptics of layered two-dimensional semiconductors and heterostructures: progress and prospects
• Temperature dependence of the electron spin g factor in GaAs
• Faraday rotation echo spectroscopy and detection of quantum fluctuations

Cited by in corpus (2)

• Theoretical investigations on Kerr and Faraday rotations in topological multi-Weyl Semimetals
• Room Temperature Optically and Magnetically Active Edges in Phosphorene Nanoribbons