Magnetic proximity effect in van der Waals heterostructures*

Monolayer transition metal dichalcogenide (TMD) are two-dimensional (2D) semiconductors that possess valley degrees of freedom. The two inequivalent valleys at K and K' form a Kramer's pair, where they are degenerate states in the presence of time-reversal symmetry. To lift this degeneracy, time-reversal symmetry must be broken, and one way of doing so is to stack TMD onto a 2D magnet. In this talk, using physically motivated models and first-principles calculations, we will address how stacking of a monolayer TMD with a 2D magnet could tune the lattice and electronic structures of TMD, with a particular focus on the control of the valley degrees of freedom. We will also address the physical consequences of interlayer coupling and proximity effects from various magnetic phases.