Fig. 3: Ferroelectric domain switching by STM/AFM tip.
From: Two-dimensional ferroelectricity in a single-element bismuth monolayer
a, AFM image of a 180° head-to-head domain wall of monolayer BP-Bi. Scale bar, 20 Å. b,c, AFM images of the same area marked by the red rectangle in a, show the reversal switching before (b) and after (c) the manipulation. Scale bars, 6.0 Å. The red dots mark the location of tip during switching. The side-view models are put in the upper panels of (a–c). d, Series of IV curves with the sample bias sweeping at different tip-sample distances (from Δz = 0 to 60 pm). The inset schematically shows how the polarization of BP-Bi changes with electric field. Red vertical bars mark the switching voltage at the positive bias side. e, Tip-height dependent switching voltage (VSW) and measured CPD (VCPD). Error bars represent the standard deviation from several measurements. f, Schematic diagram of the electric field produced by the STM/AFM tip. g, Calculated electric potential and in-plane electric field on the BP-Bi surface. Tip height z = −260 pm (a), −250 pm (b,c) and the initial tip height (Δz = 0 pm) in d,e is −50 pm relative to the height determined by the setpoint V = 100 mV, I = 10 pA above the BP-Bi surface.
