Figure 2.

The persistence of C₃ rotational symmetry in a representative aligned WS₂ spiral. (a)–(c) AFM and nonpolarized SHG mapping images of an aligned WS₂ spiral grown on a flat substrate. The zoomed-in AFM image in panel (b) shows the trace out of the dislocation spiral in the white dashed line. Scale bars: 2 μm, 0.5 μm, and 1.5 μm, respectively. (d)–(f) Polarization-resolved SHG intensity patterns at various positions labeled in panel (a), exhibiting a characteristic sixfold symmetry and thus confirming the C₃ rotational symmetry in the entire sample. Black symbols are experimental data; red curves are fitted via SH field superposition theory; blue arrows indicate the armchair direction of the sample.