Abstract
Spin transfer torque corresponds to the interaction of a spin polarized electronic current with the local magnetization: magnetic moment is
transferred from the conduction electrons to the magnetization, resulting in a change of the magnetization orientation.
This chapter introduces the physics of spin transfer torque in magnetic devices. It is meant as a tutorial and provides an elementary discussion of the basic concepts. It is not a review of the extensive theoretical and experimental work done on this subject in these last years.