Moiré Superlattices in Graphene on Twisted Hexagonal Boron Nitride

Graphene’s electronic properties can be profoundly altered by substrate-induced superlattice potentials. Theory predicts that such superlattices can generate higher-order Dirac points and open multiple mini-gaps in graphene’s band structure. These effects can be achieved by artificial patterning or by twisting atomically thin layers to form natural moiré superlattices. We explore twisted hexagonal boron nitride (hBN) as a tunable superlattice platform. In the parallel stacking configuration, twisted hBN develops triangular domains with alternating out-of-plane polarizations, producing a modulated surface potential confirmed by Kelvin probe force microscopy. Scanning tunneling microscopy and spectroscopy reveal hBN moiré patterns through graphene. The gate-dependent electronic spectra of graphene indicates strong coupling between graphene and hBN superlattice. Piezoresponse force microscopy further shows that ferroelectric and piezoelectric coupling within hBN plays a crucial role in modulating graphene’s electronic behavior, distinguishing this system from other superlattice platforms.