4. Using ferromagnets for spintronics

The classical way of manipulating the magnetization of a ferromagnetic system is based on the application of an external magnetic field combined with temperature variation. More recently, the interaction between a spin-polarized electric current (composed of electrons with different numbers of upward and downward spins) and magnetization has proved equally effective in controlling the magnetic state. On the one hand, magnetization acts on conduction electrons with a direct impact on the system's resistance; these are the magnetoresistance phenomena [E 2 135] used to detect the magnetic state. On the other hand,...