Observation of current crowding near fabricated voids in gold lines

The spatial variation of current density in lines with model void defects f abricated using focused-ion beam milling has been imaged using magnetic for ce microscopy (MFM). At current densities of 3-4x10(6) A/cm(2), an asymmetr y in the MFM signal is clearly visible at (1x1) mum(2) and (0.5x0.5) mum(2) notches at the edge of a 10 mum wide line. Comparison to a simple model ca lculation suggests that the asymmetry is due to current crowding, with the displaced current 70% localized to within 1 mum of the notch. (C) 2001 Amer ican Institute of Physics.