Physics Colloquium, David McNeill, Massachusetts Institute of Technology (MIT), USA

Abstract:

Layered magnetic insulators that can be exfoliated to the ultrathin limit are highly desirable, as we can potentially create topological states and study electron correlations by incorporating them in van der Waals heterostructures. Such materials were finally realized in 2017 with the isolation of monolayer CrI₃ and bilayer CrGeTe₃.

However, this field is in its infancy and few-layer films have complex properties different from bulk, such as the ferromagnetic to antiferromagnetic transition in CrI₃. In this talk, I will discuss our isolation and characterization of the few-layer chrome trihalides CrI₃ and CrCl₃.

We combine electron tunneling, magneto-optical, and Raman measurements, to arrive at a consistent picture correlating structural and magnetic properties of the films. The focus will be on electronic detection of magnetic states in CrI₃ and CrCl₃ using spin-filter tunneling of electrons through magnetic insulating barriers.