Rashba effect

The Rashba effect, or Rashba-Dresselhaus effect, is a momentum-dependent splitting of spin bands in two-dimensional condensed matter systems (heterostructures and surface states) similar to the splitting of particles and anti-particles in the Dirac Hamiltonian. The splitting is a combined effect of atomic spin-orbit coupling and asymmetry of the potential in the direction perpendicular to the two-dimensional plane. This effect is named in honour of Emmanuel Rashba who discovered it. Both the Rashba and Dresselhaus effects are concepts of the PhySH Physics Subject Headlines scheme.

Remarkably, this effect can drive a wide variety of novel physical phenomena even when it is a small correction to the band structure of the two-dimensional metallic state.

Additionally, superconductors with large Rashba splitting are suggested as possible realizations of the elusive Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state and the longed for topological p-wave superconductor.

Lately, a momentum dependent pseudospin-orbit coupling has been realized in cold atom systems.

The Rashba effect is most easily seen in the simple model Hamiltonian known as the Rashba Hamiltonian

where ${\displaystyle \alpha }$ is the Rashba coupling, ${\displaystyle {\boldsymbol {p}}}$ is the momentum and ${\displaystyle {\boldsymbol {\sigma }}}$ is the Pauli matrix vector. This is nothing but a two-dimensional version of the Dirac Hamiltonian (with a 90 degrees rotation of the spins).

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