On the resolution limits of tunnel magnetoresistance sensors for particle detection

Elliptical magnetoresistance sensors are analyzed with respect to their capability of high spatial resolution of particle detection. The sensor response with respect to the particle position is investigated by solving the equation of static micromagnetism. We demonstrate how the shape of the sensor can be used to obtain information about the particle position. It is verified that the external fields applied to bring particles into saturation can be utilized to tune the measurement: increasing the external fields will increase the spatial resolution of the sensor but will also reduce the visibility field in which a particle can still be detected.