Planar Hall effect and magnetoresistance in spin valve multilayers

Magnetoresistance (MR) and planar Hall effect (PHE) in spin valves were simultaneously measured in fields applied at different angles (alpha) in the film plane with respect to the easy axis of the free layer. MR curve measurements showed that the MR response to the field was linear in the alpha angle range from +/- 60 degrees to +/- 120 degrees. However, it was found that when the applied field was near perpendicular to the easy axis of the free layer, PHE curves were nonsymmetrical on both sides of the axis along the sample height. The Boltzmann transport equation was used to simulate the MR and PHE curves and determine magnetization orientation of the free layer. Results showed that the nonsymmetrical PHE curves originated from the interaction of the interlayer exchange coupling field between the pinned and free layers. Consequently, the magnetization reversal was a coherent rotation when the applied field angle alpha > 90 degrees and incoherent when alpha < 90 degrees. (C) 2001 American Institute of Physics.