Versatile Hall magnetometer with variable sensitivity assembly for characterization of the magnetic properties of nanoparticles

Highlight• A Hall magnetometer with variable sensitivity has been built. • The Hall magnetometer was calibrated and successfully compared to industry standard magnetometers. • As an application example, we estimate the mean diameter of the nanoparticles using the magnetic curves. A Hall magnetometer with variable sensitivity is constructed to measure the magnetic properties of magnetic nanoparticles manufactured by different methods. This novel magnetometer can also be used to measure bulk materials and samples in liquids. The magnetometer is constructed of two commercial Hall-effect sensors in an acrylic structure, which serves as the support for a micrometer and the circuit board with the sensors. For operation, the magnetometer acquires a complete magnetization curve in a few minutes. It has a magnetic moment sensitivity of 1.3 × 10⁻⁹ A m² at a sensitivity of 493 mV/mT, the sensitivity can be adjusted in the range of 10–493 mV/mT. Its performance is tested with magnetic nanoparticles. As an application example, we estimate the mean diameter of the nanoparticles using the magnetic curves. The results are compared with those obtained by other techniques, such as transmission electron microscopy (TEM), X-ray diffraction (XRD) and dynamic light scattering (DLS). The magnetization results are also compared with those obtained by independent commercial magnetometers, which reveal errors of approximately ±0.31 A m²/kg (i.e., 0.6%) in the saturation region.