Semiconductor Homobilayer Moiré Materials: The Difference Between K and Gamma

Moiré materials are artificial two-dimensional crystals with lattice constants that are large enough to enable large gate-controlled changes in the number of electrons per effective atom. Because their bands can have non-trivial topology related to their k-dependent sublattice eigenspinors, and have widths that are conveniently tunable, they are an ideal laboratory to assess our understanding of key issues in the theory of condensed matter. Among these are the interplay between long-range exchange interactions and lattice scale correlations and the importance of non-trivial band topology in controlling the appearance of magnetism and superconductivity. My talk will focus on understanding the qualitative differences between the electronic properties of moiré materials hosted in the valence bands of K and Gamma valley transition metal dichalcogenide homobilayers. I will specifically discuss the role of long-range Coulomb interactions, design rules for spin and orbital magnetism in both metallic and insulating states, and the absence of superconductivity (so far) in both cases.