Fig. 4: Local negative capacitance around polar Bloch points revealed by the phase-field simulations.
a The isosurface of εzz = −5000 (green) overlaid with that of Pmag = 0.55 Ps (red). The chains of two types of Bloch points are marked by purple and yellow circles. b The local polarization around a DDC-type Bloch point with the xy and xz cross-sections passing through the Bloch point. c, d The mappings of the polarization magnitude overlaid with the polarization vectors of the horizontal (c) and vertical (d) slices of the Bloch point. e, f The corresponding mappings of the electric field overlaid with the normalized electric field vectors of the two slices in c, d. g, h The profiles of the polarization and electric field (g) and εzz (h) along the dashed lines in d and f. The red and blue background colors represent the regions of positive and negative capacitances, respectively.
