Fig. 2: Polar vortices forming in the two stacking layers.
From: Polar vortex hidden in twisted bilayers of paraelectric SrTiO3
a Depth profiles of the phases integrated over Sr atomic columns in the nonoverlapping region (between AA and AB stacking regions) of the moiré patterns. The position of the interface is indicated with a black star (the 40th slice). The interface region is indicated with dashed lines. b Phase image of the interface (the 40th slice). c, e Polar displacement mapping in the depth of 12.0 nm (top layer) (c) and 23.2 nm (bottom layer) (e). Regions with AA and AB stacking sequences are marked with yellow and red circles, respectively. The 10-pm arrow in (e) is a reference for the magnitude of the polar displacement. d, f Vorticity (∇⨯P)[001] distribution corresponding to (c) and (e). The vorticity is in the unit of 1010 C/m3. Scale bars, 2 nm.
