Event Details

Condensed Matter Seminar

Van der Waals heterostructures formed of two-dimensional crystals with controlled twisting angles between the layers have opened the path for designing thin materials with novel properties. In this study, we demonstrate the presence of alternating out-of-plane polarisation domains in 3R-MoS_2 bi-layer heterostructures, giving rise to room-temperature (RT) ferroelectric behaviour (see representative schematics and an optical image shown in figures 1(a) and (b)). Movement of the domains is visualised using channelling contrast electron microscopy, while the interfacial charge transfer for the observed ferroelectric domains is quantified using Kelvin probe force microscopy (KPFM). The latter shown in figures 1(c) and (d). Modelling has been performed to predict the aforementioned charge transfer between the domains, the movement of the domain walls and their bending rigidity. Finally, proof-of-principle field-effect transistors have been produced and measured, showing a channel resistance that exhibits a pronounced hysteresis governed by pinning of the ferroelectric domain walls. These results show the huge potential offered by twisted 2D heterostructures for the development of RT ferroelectric devices.

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