THE EFFECTS OF PINNING MAGNETIZATION WITH GEOMETRICAL FEATURES IN THIN PERMALLOY-FILMS

This work considers the use of geometric alterations to the edges of a strip of thin magnetoresistive material used to make a magnetometer device. The geometric features in the form of narrow fins are intended to improve the performance of the device by pinning the magnetization at the strip edges at an angle corresponding to the high sensitivity region of the magnetoresistance curve, thus including this region in the contribution to total resistance change. Both theoretical calculations using a micromagnetic model and experimental work on a prototype device are described. Results show that the device behaves closely to the modeling predictions, exhibiting a large sensitivity of 17 muV/V/muT, 70% greater than a more conventional device, with the additional capability of a trimmable orthogonal field rejection. Differences between the predicted and measured devices are described in terms of the shortcomings of the model and to domain activity in the device.