FIG. 2: (a) 12 nm × 12 nm STM image and (b) (c) FT of two areas each enclosed with a square in sample B. Sample B was measured at V$_{s}$= -350 mV and I$_{t}$= 0.4 nA at T= 6.3 K. The blue line is the domain wall between the clockwise phase and the anticlockwise phase. 10