Ferromagnetism in ultra-thin van der Waals materials*

The isolation of atomically-thin crystalline layers with long-range magnetic order would open the door to new prospects in van der Waals heterostructures such as their use in spintronics. Though local magnetic moments may be introduced in 2-D crystals via doping or defect engineering, the vast majority of these materials are intrinsically non-magnetic. The family of the transition metal trihalides is an exception. We use the magneto-optical effect to study few-layer samples of a member in this family: chromium triiodide (CrI3). We will report on our measurements of magnetization and Curie temperature, as well as the determination of the critical behavior and universality class.