In-plane vector magnetometer employing a single unbiased magnetoresistor

This paper extends previous work, where a single barber-pole magnetoresistor (MR) was employed for measuring simultaneously two magnetic field components. The present work differs from the previous one in employing a single unbiased MR, which is simpler and less expensive. The present arrangement, like the previous one, relies on a rotating excitation method. A specially devised elliptically rotating field is employed for this purpose. The latter causes the material magnetization to rotate uniformly when there is no external field present. The presence of an external magnetic field is detected by measuring the tune shifts of the resulting MR ac output zero-crossings. Despite the similarity between the present system and its previous counterpart, the sensitivities of detection of the present arrangement are equal for the two orthogonal components of the externally measured field. It is also interesting that the intensities of the sinusoidal excitation fields in the present case are equal. However, the excitation coils are not perpendicular to each other as they were in the previous barber-pole case.