Ferroelectric Hysteresis in Singly Aligned Graphene-hBN Moiré Superlattices

Ferroelectric materials have the unique ability to maintain an electric polarization which can be reversed under an external applied electric field. This property makes them valuable for applications such as non-volatile random-access memories, transducers, actuators and electro-optic modulators. Recently, emergent unconventional ferroelectricity is demonstrated in moiré superlattices of bilayer graphene and hexagonal boron nitride (hBN) hosting non-centrosymmetric stacking order. Whether this phenomenon is also present in non-centrosymmetric single layer graphene (SLG)-hBN moiré superlattices is still under debate. Here a ferroelectric response is demonstrated in an SLG-hBN moiré superlattice. Through Hall measurements, the origin of the hysteretic behavior is pinpointed to abnormal charge screening due to the moiré superlattice band and the spontaneous polarization magnitude in the moiré superlattice structure is estimated. Temperature dependent measurements confirm that the hysteretic behavior persists from 2K up to room temperature, opening opportunities for high-mobility, ultrathin non-volatile devices.