Spin energy enhanced by exchange interaction in a Rashba spintronic system in quantizing magnetic fields

Using the standard Hartree-Fock approximation on the basis of the random-phase approximation, we calculate the self-energy induced by exchange scattering due to electron-electron interaction in a spin-polarized two-dimensional electron gas (2DEG) system. Applying the exchange self-energy to a Green's function approach, we examine how the exchange interaction affects the spin-splitting in a 2DEG with the Rashba spin-orbit interaction and Zeeman spin-splitting in the presence of quantizing magnetic fields. It is demonstrated that such a many-body interaction can lower the energy levels of the system and enhance significantly the spin-splitting around the Fermi level. We also find that the exchange-enhanced spin-splitting is achieved mainly via intra-Landau-level scattering channels and the spin energy oscillates with the magnetic fields.