To create spintronic devices requires the presence of its two main components — a source of spin-polarized electrons (i.e., the source generating the electrons predominantly in one direction back) and a receiving system sensitive to the spin polarized electrons (spin detector). Manipulation of the spin of the electrons in the transport process between the source and the detector are realised by means of an external magnetic field or by means of effective fields caused by spin-orbit interactions. The easiest way to generate spin-polarised current is to pass current through a ferromagnetic material. A typical GMR device (a device based on giant magnetoresistance) consists of at least two layers of ferromagnetic material and the separation of conductive non-magnetic layer. In that case, if the vectors of magnetization of the ferromagnetic layers are collinear, the electrical resistance will be minimal (respectively, there will be the greatest power the current flow); in the case of the opposite vector direction of magnetization, the current value will be minimal.