Rashba effect

As Rashba effect is called a specific coupling of the electron spin to the orbital motion of the electron. There is a significant effect of the spin -orbit coupling, whose contribution to the electron energy is well known, is proportional to the cross product of the electric field E at the position of the electron and its momentum p, scalar multiplied by the spin σ, Δ E ~ [E xp ] σ. It is crucial that the inversion of the asymmetric structure of the present system, more precisely, that the potential, which is the electron gas in two - dimensions includes (2DEG ) asymmetrical. This has been in spin field- effect transistors (spin -FETs) at low temperatures in certain high-purity semiconductor heterostructures such as In (0.53 ) Ga (0.47 ) As / In (0.52 ) Al (0.48 ) As implemented: the ( extrinsische! ) influencing of the spins takes place here by means of a voltage that can be controlled by a gate electrode. The electric field is perpendicular to the direction of movement of the electron, ie perpendicular to the observed surface or interface, and causes - considered classic - a precession which changes the spin orientation. Correct the spin -orbit coupling is described by the Dirac equation by a special term development.

The Rashba term is often compared to the so-called Dresselhaus effect, also a symmetry effect, but which is completely intrinsic and differs from the Rashba effect in such essential respects (eg, in the above-mentioned asymmetry).

Importance

At present ( end of 2010) of the Rashba effect, inter alia, discussed at crystal surfaces and interfaces related to the occurrence of certain topological excitations, eg in connection with so-called Skyrmion excitations. Moreover, the effect has outstanding importance in spintronics. In this effect, hence the concept of spin transistors, many semiconductor researchers working on its realization at the moment. The starting material are typically so-called semiconductor heterostructures. It is expected from spin transistors further miniaturization of components and shortening the shift times.