Electrical Spin Injection: Spin-Polarized Transport from Magnetic into Non-Magnetic Semiconductors

Abstract

Spin polarized transport in semiconductors presently attracts a great deal of interest. For the past five years or so, several research groups have tried to achieve efficient injection of spin polarized electrons into non-magnetic semiconductors using ferromagnetic metals as spin injecting contacts. All these experiments have failed to produce conclusive results; the reasons for this lack of success were outlined in Chap. 2 and in [1]. The main outcome of the theory for spin injection given in Chap. 2 is that the spin polarization a in the semiconductor is simply not proportional to the bulk spin polarization β in the ferromagnet. This is mainly due to the different conductivities of semiconductor (σ _sc ) and ferromagnet (σ _fm ) and to the short spin scattering length λ _fm in the ferromagnet.