Figure 3
(a)-(f) STS conductance maps showing real space ZFC vortex lattice image at 350 mK along with their Fourier transforms. Delaunay triangulation of the VL are shown as solid lines joining the vortices and sites with 5-fold and 7-fold coordination are shown as red and white dots respectively. The disclinations (unpaired 5-fold or 7-fold coordination sites) observed at 26 and 30 kOe are highlighted with green and purple circles. While all images are acquired over 1 μm × 1μm area, images shown here have been zoomed to show around 600 vortices for clarity. The Fourier transforms correspond to the unfiltered images; the color scales are in arbitrary units. The expanded view of the defect structure inside the region bounded by the yellow boxes are shown for the VL at 25 and 30 kOe next to panels (d) and (f) respectively. The images between 20-30 kOe were recorded in the same magnetic field ramp, whereas the image at 15 kOe was recorded in a separate magnetic field ramp on the same cleaved surface. The mis-orientation of the VL at 15 kOe with respect to the other images is due to a small rotation of the sample holder due to vibration during the liquid 3He regeneration process between two magnetic field ramps. (g)-(h) VL images (400 nm × 400 nm) at 32 kOe and 34 kOe. At these fields the VL image becomes blurred due to the motion of vortices.
