Quantitative current measurements using scanning magnetoresistance microscopy

We have demonstrated the capability of scanning magnetoresistance microscope (SMRM) to be used for quantitative current measurements. The SMRM is a magnetic microscope that is based on an atomic force microscope (AFM) and simultaneously measures the localized surface magnetic field distribution and surface topography. The proposed SMRM employs an in-house built AFM cantilever equipped with a miniaturized magnetoresistive (MR) sensor as a magnetic field sensor. In this study, a spin-valve type MR sensor with a width of 1 μ m was used to measure the magnetic field distribution induced by a current carrying wire with a width of 5 μ m and a spacing of 1.6 μ m at room temperature and under ambient conditions. Simultaneous imaging of the magnetic field distribution and the topography was successfully performed in the DC current ranging from 500 μ A to 8 mA. The characterized SV sensor, which has a linear response to magnetic fields, offers the quantitative analysis of a magnetic field and current. The measured magnetic field strength was in good agreement with the result simulated using Biot–Savartʹs law.