Anomalous magnetoresistance behavior of CoFe nano-oxide spin valves at   low temperatures
  We report magnetoresistance curves of CoFe nano-oxide specular spin valves of MnIr/CoFe/nano-oxidized CoFe/CoFe/Cu/CoFe/nano-oxidized CoFe/Ta at different temperatures from 300 to 20 K. We extend the Stoner-Wolfarth model of a common spin valve to a specular spin valve, introducing the separation of the pinned layer into two sublayers and their magnetic coupling across the nano-oxide. We study the effect of different coupling/exchange (between the antiferromagnetic layer and the bottom sublayer) field ratios on the magnetization and magnetoresistance, corresponding with the experimentally observed anomalous bumps in low temperature magnetoresistance curves. 
J. Ventura, J. B. Sousa, M. A. Salgueiro da Silva, P. P. Freitas and   A. Veloso