Abstract
A Current-induced magnetic field was detected by magnetic force microscopy (MFM) in order to evaluate a current flowing in a fine structure. Our system consists of a conventional magnetic force microscope and a feedback system for elimination of electrostatic force. As a first step in investigating the quantitativeness of this method, we observed the magnetic field around sub-micron-width gold wires where two currents joined with a third. First, we confirmed that the detected magnetic force signals qualitatively agreed with distribution of the magnetic field gradient around the sample. The amplitude of the magnetic force signal around the individual current paths was proportional to the current value. By taking account of the strength of the current-induced magnetic field, we theoretically estimated the amplitude ratio between the two different current paths. We then investigated the difference between the magnetic force signals observed around those current paths, and found that the experimental results quantitatively agreed with the theoretical values to some extent.
