Rotating-field magnetoresistance of exchange-biased spin valves -: art. no. 023910

We investigate the magnetoresistance (MR) of spin valves by (i) varying the strength of the field applied in a fixed direction and (ii) rotating the field with fixed strength. The latter data reflect in general a mixture of giant and anisotropic magnetoresistance (GMR and AMR). We present an experimental procedure to suppress the AMR contributions of all ferromagnetic layers in the spin valve without disturbing the GMR response. The resulting angular MR curves are fitted with a single-domain model to determine with high precision the exchange bias field, the uniaxial anisotropies, the GMR ratio, and the interlayer coupling field. The application of the method to differently prepared Ta(5.0 nm)/NiFe(3.0 nm)/FeMn(15.5 nm)/NiFe(3.0 nm)/Co(2.0 nm)/Cu(3.5 nm)/Co(2.0 nm)/NiFe(7.0 nm) spin valves with GMR ratios of 1.8% and 4% demonstrates the sensitivity and reveals differences of the order of a few percents of the exchange bias field for the uniaxial anisotropy fields of the free and pinned layer as well as for the interlayer coupling field. (C) 2005 American Institute of Physics.