The rise of non-vdW moiré superlattices

The formation of a moiré superlattice is induced by the stacking of van der Waals (vdW) 2D materials with a twist angle or small lattice mismatch. This superlattice functions as a periodic potential for electrons, forming moiré flat bands with emerging quantum phenomena or highly correlated states. It has emerged as one of the most significant advancements in condensed matter physics in recent decades. However, the vdW interactions between adjacent layers result in weak interlayer coupling and narrow energy splitting of the flat bands at a range of tens of millielectron-volt (meV). Consequently, electrons are weakly localized and easily disturbed by thermal fluctuations, hindering the development of strongly correlated phenomena at room temperature.