Fig. 3: Edge ferroelectricity in a Te nanosheet.
a Upper and lower: SEM and AFM topographical images of a Te nanosheet (height of ~15 nm) on an Au-coated silicon wafer. b Values of d33 at the different marked positions (overlaid on an AFM topograph) of the Te nanosheet, showing that d33 at the edge is about 80% higher than that inside of the nanosheet. c OFF-field PFM phase hysteresis loops from the edge to the inside of 2D Te nanosheet, showing ferroelectric domain with edge width <200 nm. Upper part is a schematic height profile of the edge and vertical arrows mark locations where individual PFM traces were measured. Vertical PFM phase mapping before electric poling (d), after poling at +2.5 V (e), after poling at −2.5 V (f), overlaid on 3D topography image of the Te nanosheet. c–f were measured with VAC = 1.5 V driving on the corresponding local resonance frequency.
