Quantitative interpretation of the magnetoresistive response (amplitude and shape) of spin valves with synthetic antiferromagnetic pinned layers

We present an analytical calculation of the shape of the magnetoresistive r esponse of spin-valve structures with synthetic antiferromagnetic pinned la yer, i.e., of the form buffer/ferromagnet1/Cu/ferromagnet2/Ru/ferromagnet3/ antiferromagnet. The magnetization reversal in the three magnetic layers is assumed to occur via coherent rotation. An analytical expression of the wh ole hysteresis loop is given as a function of the characteristic parameters of the system (coupling strength through the Ru spacer, ferromagnet3/antif erromagnet pinning energy). We also extended a code based on the Boltzmann equation of transport to calculate the giant magnetoresistance (GMR) amplit ude in these structures from the microscopic transport parameters. In order to explain the relatively high GMR amplitude experimentally observed in su ch spin valves, it is shown that some degree of specular reflection must be introduced at the ferromagnet2/Ru interface. Good agreement with both the shape and amplitude of the experimental magnetoresistance curves can be obt ained. (C) 2000 American Institute of Physics. [S0021-8979(00)01907-1].