RESUMO
Using thin film pillars approximately 100 nm in diameter, containing two Co layers of different thicknesses separated by a Cu spacer, we examine the process by which the scattering from the ferromagnetic layers of spin-polarized currents flowing perpendicular to the layers causes controlled reversal of the moment direction in the thin Co layer. The well-defined geometry permits a quantitative analysis of this spin-transfer effect, allowing tests of competing theories for the mechanism and also new insight concerning magnetic damping. When large magnetic fields are applied, the spin-polarized current no longer fully reverses the magnetic moment, but instead stimulates spin-wave excitations.
RESUMO
Current-induced switching in the orientation of magnetic moments is observed in cobalt/copper/cobalt sandwich structures, for currents flowing perpendicularly through the layers. Magnetic domains in adjacent cobalt layers can be manipulated controllably between stable parallel and antiparallel configurations by applying current pulses of the appropriate sign. The observations are in accord with predictions that a spin-polarized current exerts a torque at the interface between a magnetic and nonmagnetic metal, due to local exchange interactions between conduction electrons and the magnetic moments.
