Magnetic nanoparticles as components of magnetoresistance sensors: the gGMR-sensor

The granular giant magnetoresistance effect is employed for the conceptional design of a novel type of magnetoresistive sensor. By solving the Landau-Lifshitz equation for a set of homogeneously magnetized spheres arranged in an ordered monolayer of cubic or hexagonal symmetry, we found the absence of exchange coupling between spatially separated magnetic material to result in the antiparallel alignment of contiguous magnetic nanoparticles. The switching behaviour of these arrays is soft in comparison to continuous sensors and the influence of the component properties on the response functions indicate constructive methods to tailor the sensor characteristics to specific needs by the employment of selected particles. Further, we will show that in the case of low distance measurements, an increased sensitivity, in comparison to the conventional magnetoresistance sensors, is bought at the cost of an inherent device noise.