Dataset for "Polar Discontinuities, Emergent Conductivity, and Critical Twist-Angle-Dependent Behaviour at Wafer-Bonded Ferroelectric Interfaces"

Abstract

Atomic Force Microscopy data associated with the submitted paper: "Polar Discontinuities, Emergent Conductivity, and Critical Twist-Angle-Dependent Behaviour at Wafer-Bonded Ferroelectric Interfaces", Nature Communications. Abstract for paper: "Probing novel functional properties, arising from twisted interfaces, has traditionally relied on the stacking of exfoliated 2D materials and the spontaneous formation of van der Waals (vdW) bonds. So far, investigations involving more intimate covalent or ionic bonds have not been a major focus. Yet, we show here that an established technique, involving high temperature thermocompressional bonding of bulk single crystalline wafers, works well for creating twisted non-vdW interfaces. We have successfully bonded z-cut lithium niobate single crystals to deliberately create ferroelectric oxide interfaces with strong polar discontinuities and have mapped the associated emergent interfacial conductivity. In some instances, a dramatic change in microstructure occurs, involving local dipolar switching. Such behaviour implies a twist-induced collapse in the capability of the system to effectively screen interfacial bound charge. Importantly, this phenomenon only occurs around specific moiré twist angles which have sparse coincident lattices and associated short-range aperiodicity. In quasicrystals, aperiodicity is known to induce pseudo-bandgaps and we suspect a similar phenomenon here.