Modeling and measurement of spin torques in current-perpendicular-to-plane giant magnetoresistive (invited)

This paper discusses some aspects of practical modeling of spin-torque effects in current-perpendicular-to-plane (CPP) giant magnetoresistive magnetic multilayers, with emphasis on considerations of primary importance for sensor and/or read head applications of CPP spin valves (SVs). These include an extension of the well-known Valet-Fert transport model [Phys. Rev. B 48, 7099 (1993)] to the general case of noncollinear magnetization vectors in CPP multilayer of arbitrary layer structure as well as the application of the model to realistic CPP-SV structures. Simple analytical models for the angular dependence of spin-torque critical currents in CPP-SV devices are reviewed and compared with numerical simulations which include thermal fluctuations. Finally, the paper also contains some recent high frequency spectral measurements of spin-torque-induced noise in dual spin-valve sensors. (C) 2006 American Institute of Physics.