Polar magneto-optical Kerr effect spectroscopy with a microscope arrangement for studies on 2D materials.

The article focuses on the development and validation of a magneto-optical Kerr effect (MOKE) spectroscopy setup designed for high spatial resolution measurements on microscopic samples, such as two-dimensional material flakes. The setup employs a microscope-like optical arrangement with a 90° twisted periscope mirror configuration that preserves the circular polarization state of light and enables polar MOKE measurements using a conventional H-frame electromagnet without holes in the pole pieces. A Jones matrix analysis was conducted to understand and correct the influence of optical elements, particularly the beam-splitter, on the measured Kerr rotation (ϕ) and ellipticity (η) signals. The functionality of the system was demonstrated through measurements on 2H-WS₂ flakes at low temperature, with results verified by Kramers–Kronig relations and simulations, allowing extraction of the Landé g-factor of the ground state exciton consistent with prior studies.