2D Magnetism in transition metal halides

Newly discovered intrinsic magnetic two-dimensional material down to monolayer greatly expands the family of 2D materials and invokes tremendous interests in novel magnetic related applications in 2D limit. In this work, by using compound source molecular beam epitaxy (CS-MBE), we prepared high-quality monolayer and bilayer transition metal halides, including dihalides and trihalides on Highly Oriented Pyrolytic Graphite (HOPG) substrates. Scanning tunneling microscopy was employed to determine their atomic and electronic structure. The magnetic properties are characterized in-situ by spin-polarized STM and ex-situ by vibrating-sample magnetometer. We demonstrated the existence of ferromagnetism as well as antiferromagnetism in the 2D limit. In addition, we found the interlayer coupling in bilayer CrBr3 depends strongly on the stacking order and can be either ferromagnetic or antiferromagnetic.