Quantitative investigation of FeMn-based spin-valves by rotating field magnetoresistance measurements

We measure the magnetoresistance of Ta/NiFe/FeMn/NiFe/Co(tCo)/Cu/Co(tCo)/NiFe spin-valves as a function of field strength and direction. The exchange bias HEB and the giant magnetoresistance depend on the Co thickness tCo, and the resistance shows rotational hysteresis when the external field is close to compensating HEB. A single-domain model reproduces the angular dependence of the magnetoresistance in regions without hysteresis, yields HEB values in agreement with MOKE, and allows one to precisely determine the interlayer coupling and uniaxial anisotropies although they are much weaker than HEB.