Figure 2. MFM images taken at the same location during field sweep at 150 K.

(a–g), (h–p), (q–w) and (x–b′) are four image series, which correspond to the four numbered paths in the transport measurements. The sample is first cooled from room temperature to 150 K and then the magnetic field is applied perpendicular to the film plane. The scale bar in a is 2 μm and the scanned areas are 8.5 μm × 8.5 μm for all images. The colour scales for a–b′ are 0.6, 0.6, 0.6, 0.4, 0.4, 0.4, 0.4, 1.2, 1.2, 1.5, 2, 2, 2.5, 3, 0.4, 0.3, 1, 0.6, 2.0, 0.8, 0.6, 0.3, 0.3, 1.5, 2.5, 2.5, 2.5 and 0.3 Hz, respectively. The insets in c and r are the fast Fourier transformation patterns of 14 μm⁻¹ × 9.0 μm⁻¹, exhibiting evident dumbbell-like density distribution in both cases. The white arrows in j and k indicate sharp discontinuities, and the dark and white arrows in l denote the growing of existing and new COI domains at a fixed field 1.2 T, respectively. Low contrast ripples seen in f,g,v and w are from topography.