In Franz’s work he presented an analysis of the magnetic anisotropy that enables 2D ferromagnetism in CrI₃ , one of the first 2D ferromagnets discovered. He determined the most general microscopic spin interactions allowed by this material’s crystal symmetries and estimate the strength and sign of these interactions by fitting angle-dependent ferromagnetic resonance data using this spin model. He also presented a symmetry analysis of the most general forms of tensors describing physical responses in 2D materials composed of a honeycomb lattice of edge-sharing octahedra relevant for the aforesaid materials. [Link to his thesis]