Figure 2. Bright-field (BF) TEM images and holographic magnetic field maps of chains of ~15 nm Co particles that are (i) one, (ii) three and (iii) multiple nanoparticles in width.
Initial remanent magnetic states (IS) and magnetic states after application of a field of ±2 T are shown. The white contours and the colors (described using the color wheel) provide a measure of the magnitude and direction of the projected magnetic field in the plane of the particles with a spatial resolution of ~6 nm. Each white contour represents a phase variation of π/64, corresponding to 1/64 of a flux quantum φ0 = 2.07·10−15 T·m2 enclosed between two adjacent contours.