Magnetic microscopy using Hall effect sensors biased with pulsed currents

Abstract

In this article, we describe the programs for instrument control, data acquisition, and analysis developed to adapt a Scanning Magnetic Microscope for the Delta Mode technique. This adaptation led to the elimination of thermoelectric effects and introduced a novel approach to data acquisition during mapping by employing a pulsed current bias for Hall effect sensors. When comparing the adapted system to a commercial magnetometer, we observed average errors of 1.2 % in the measurement of saturation magnetization, utilizing a nickel sphere with 99 % purity. Furthermore, through a sample holder with three cylindrical cavities, we investigated a methodology to characterize samples at the microgram level with different magnetizations, simulating the interaction between the induced magnetic fields. The theoretical and experimental results emphasized the geometric possibilities in the design of a sample holder to estimate magnetizations of various samples simultaneously, demonstrating the effectiveness of the Scanning Magnetic Microscope with Delta Mode.