Raman spectroscopy of phonons and their coupling to excitons and layered magnetism in 2D magnet CrI3*

Two-dimensional (2D) materials with intrinsic ferromagnetism have attracted massive interest because of their potential applications in data storage and spintronics devices. Atomic layers of chromium triiodide (CrI3) are one of such 2D ferromagnetic (FM) materials that have been demonstrated to realize long range FM order in its monolayer limit. In this talk I will show our Raman spectroscopy studies of electron-phonon coupling and coupling between an Eg phonon and layered magnetism in 2D CrI3. Our magneto-optical studies of twisted double bilayer CrI3 will also be discussed. Our results reveal the emergence of finite net magnetization that originates from spin frustrations introduced by moiré superstructures in twisted double bilayer CrI3.