Fig. 3: 3D topology of moiré vortex patterns.
From: Strain-induced moiré polar vortex in twisted paraelectric freestanding bilayers
a Schematic image of IP polar texture dependent on depth in the top layer. b Simulated vortex patterns in the top layer with θt = 10.43°, with colored tubes representing their IP vorticity. c Zoomed-in figure of one selected vortex period in (b). d The double-well potential of free energy in the absence (I) and presence (II) of flexoelectric energy. e The cross-sectional view in (010) and (\(\bar{1}\)10) respectively in (b), where color indicates the IP vorticity. The scale bar represents 1 nm. Schematic image of the topology of a chiral vortex in the lower-half layer at position B (f), which can be recognized as the combination of curling and divergent polar textures (g). Color in (f, g) depicts the IP polarization rotation and OP orientation, respectively.
