Fig. 2: Reconstructed polar two-order radial vortex in one nanostructure.
From: Observation of multi-order polar radial vortices and their topological transition
a The vertical PFM amplitude (V-amp.) and vertical PFM phase (V-pha.) images of one nanoisland. b–d The lateral PFM amplitude (L-amp.) and lateral PFM phase (L-pha.) images of one nanoisland with sample rotation for 0° (b), 45° (c) and 90° (d), respectively. Blue arrows in (a–d) denoting the cantilevers of PFM tips. e A planar-view HAADF-STEM image showing the nanoislands in BFO film. f Enlarged HAADF-STEM image for one nanoisland. g–j Polarization distribution of BFO corresponding to the regions numbered 1, 2, 3 and 4 in (f), respectively. k Enlarged V-pha. image (top panel) and HAADF-STEM image (bottom panel) around one nanoisland, displaying the out-of-plane and in-plane polarization distribution, respectively. l–n Reconstructed 3D polarization distribution around one nanoisland, suggesting the polar topological state of two-order radial vortex.
