Rashba–Edelstein effect

Not to be confused with the Bychkov–Rashba effect, sometimes also known as the Rashba effect.

The Rashba–Edelstein effect (REE) is spintronic phenomenon in which a two-dimensional charge current generates a surface spin accumulation. This effect is an intrinsic charge-to-spin conversion mechanism and it was predicted in 1990 by the scientist V. M. Edelstein. It was demonstrated in 2013 and confirmed by experimental evidence in the following years.

The origin of the effect can be ascribed to the presence of spin-polarized surface or interface states. Indeed, a structural inversion symmetry breaking (asymmetry) causes the Rashba effect to occur: this effect breaks the spin degeneracy of the energy bands and causes the spin polarization to be locked to the momentum in each branch of the dispersion relation. If a charge current flows in these spin-polarized surface states, it generates a spin accumulation. In the case of a bidimensional Rashba gas, where this band splitting occurs, this effect is called the Rashba–Edelstein effect.

For a class of peculiar materials called topological insulators, spin-split surface states exist independently from the Rashba effect, due to the surface topology. Topological insulators display a spin-split linear dispersion relation on their surfaces (i.e., spin-polarized Dirac cones), while having a band gap in the bulk (this is why these materials are called insulators). Also in this case, spin and momentum are locked, and, when a charge current flows in these spin-polarized surface states, a spin accumulation is produced; this is called the Edelstein effect. In both cases, a 2D charge-to-spin conversion mechanism occurs.

The reverse process is called the inverse Rashba–Edelstein effect, in which a spin accumulation is converted into a bidimensional charge current, resulting in a 2D spin-to-charge conversion.

The Rashba–Edelstein effect and its inverse effect are classified as spin-charge interconversion (SCI) mechanisms (another example is the spin Hall effect). Materials that display these effects are promising candidates for future technological applications such as spin injectors and detectors.

The Rashba–Edelstein effect is a surface effect, whereas the spin Hall effect is a bulk effect. Another difference between the two is that the Rashba–Edelstein effect is a purely intrinsic mechanism, while the spin Hall effect origin can be either intrinsic or extrinsic.

This article is issued from Wikipedia. The text is available under Creative Commons Attribution-Share Alike 4.0 unless otherwise noted. Additional terms may apply for the media files.