Magnetic-field measurements of current-carrying devices by force-sensitive magnetic-force microscopy with potential correction

A scanning probe technique for current-carrying device imaging is proposed that combines magnetic-force microscopy with surface-potential nulling measurements. The device is ac biased at an off-resonant frequency and the current-induced magnetic field results in cantilever deflection which is detected by a lock-in amplifier. An ac bias at the resonant frequency is simultaneously applied to the tip and conventional scanning surface-potential microscopy feedback is used to match the tip and surface potentials. This multiple-modulation technique allows electrostatic and magnetic interactions to be distinguished and surface-potential and magnetic-force images to be collected simultaneously. The technique, which is referred to as potential-correction magnetic-force microscopy, produces force rather than force-gradient images as in conventional magnetic-force microscopy. Further prospects for potential-sensitive magnetic-force imaging are discussed. (C) 2001 American Institute of Physics.