Superlubric sliding ferroelectricity

Abstract: Sliding ferroelectricity may emerge in many van der Waals bilayers/multilayers and the low switching barriers render ultrafast data writing with low energy cost. We note that such barriers are still much higher compared with structural superlubricity, and in this paper we propose a type of superlubric sliding ferroelectricity in homobilayers separated by a different layer that leads to unprecedented low switching barriers due to incommensurate interfaces. For example, the switching barrier of 3R bilayer MoS2 will be respectively reduced by around 2 or 1 order of magnitudes if they are separated by a graphene or BN monolayer, and the required voltage for switching can be about 1 order of magnitude lower. Such superlubric sliding ferroelectricity widely exists in various similar sandwich trilayer systems where the polarizations stem from symmetry breaking in across-layer stacking configurations, and with ultralow barriers of superlubric sliding, their performances for various applications are greatly enhanced compared with homobilayer sliding ferroelectrics.