ABSTRACT
Switching of Magnetization.........................................................................153 7.4 Quantitative Theory of Spin-Transfer Torque .............................................166
7.4.1 General Principles ............................................................................166 7.4.2 Keldysh Formalism for Fully Realistic Calculations
of the Spin-Transfer Torque.............................................................169 7.5 Quantitative Results for Co/Cu/Co(111) .....................................................172 7.6 Summary ......................................................................................................175 Acknowledgments..................................................................................................175 References..............................................................................................................175
Recently there has been a lot of interest in magnetic nanopillars of 10 to 100 nm in diameter. The pillar is a metallic layered structure with two ferromagnetic layers, usually of cobalt, separated by a nonmagnetic spacer layer, normally of copper. Nonmagnetic leads are attached to the magnetic layers so that an electric current may be passed through the structure. In the simplest case, the pillar may exist in two states, with the magnetization of the two magnetic layers being parallel or antiparallel. The state of a pillar can be read by measuring its resistance, this being smaller in the parallel state than in the antiparallel one. This dependence of the resistance on magnetic configuration is the giant magnetoresistance (GMR) effect.
