Magneto-optics for detecting and controlling the magnetization of two-dimensional magnetic materials

If you make materials extremely thin, their properties change. Some materials, such as graphite, already consist of thin layers of one or a few atoms thick, that are neatly stacked on top of each other. These are called van der Waals materials. In his thesis, Freddie Hendriks investigated the magnetic properties of the van der Waals matarial Cr2Ge2Te6 (CGT). The magnetic CGT can be stacked relatively easy with other van der Waals materials, to combine the properties of the different materials. These nanometer thin magnetic stacks could find applications in future computer chips as memory elements, or as the basis for new kinds of chips that process information based on the spin rather than the charge of electrons.

By shooting at it with a laser, and measuring how the polarization of the laser changes, Hendriks was able to measure the magnetization of a thin layer of CGT. By measuring the magnetization under various conditions, he determined the magnetic properties. Hendriks discovered for example that magnetic CGT not only changes the polarization of light, but that polarized light also has a large effect on the magnetization of CGT. By comparing these measurement results to various theoretical calculations, Hendriks found that the excitonic states of CGT play an important role in the interaction between magnetism and light.

Dissertation: https://hdl.handle.net/11370/b8223ff8-2542-4e7c-9a5f-849587f76163