The spatial variation of current density in lines with model void defects fabricated using focused-ion beam milling has been imaged using magnetic force microscopy (MFM). At current densities of 3-4 × 106 A/cm2, an asymmetry in the MFM signal is clearly visible at (1 × 1) μm2 and (0.5 × 0.5) μm2 notches at the edge of a 10 μm wide line. Comparison to a simple model calculation suggests that the asymmetry is due to current crowding, with the displaced current 70% localized to within 1 μm of the notch. © 2001 American Institute of Physics.
