Magnetoresistance sensor with an out-of-plane magnetized sensing layer

A concept for a linear and reversible magnetoresistance sensor is demonstrated using a magnetic spin valve. The sensor is based on coherent rotation of an out-of-plane magnetized sensing layer in parallel-to-plane applied magnetic fields. For Pt/CoFe sensing layers, the sensor response depends critically on the perpendicular magnetic anisotropy of the CoFe film and, therefore, on its thickness t(CoFe). Sensors with small t(CoFe) exhibit a high linearity up to applied fields of about 50 mT, but their magnetic field sensitivity is rather small. The sensitivity, however, increases with t(CoFe) and it reaches its maximum value just below the spin reorientation transition in the CoFe sensing layer. (c) 2005 American Institute of Physics.