Magnetism and quantum melting in moiré-material Wigner crystals

Abstract

Recent experiments have established that semiconductor-based moiré materials can host incompressible states at a series of fractional moiré-miniband fillings. These states have been identified as generalized Wigner crystals in which electrons localize on a subset of the available triangular-lattice moiré superlattice sites. In this article, we use momentum-space exact diagonalization to investigate the many-body ground-state evolution at rational fillings from the weak-hopping classical-lattice gas limit, in which only spin degrees-of-freedom are active at low energies, to the strong-hopping metallic regime where the Wigner crystals melt. We specifically address the nature of the magnetic ground states of the generalized Wigner crystals at fillings 𝜈������=1/3 and 𝜈������=2/3.