Nuclear-spin relaxation and spin excitons in a two-dimensional electron gas

The nuclear-spin relaxation in the vicinity of a two-dimensional electron channel is considered in terms of the creation and annihilation of spin excitons. This approach provides a qualitative picture of the competition between the inhomogeneity of the channel and the Coulomb repulsion of the electrons. The spin-flip processes are allowed energetically in the presence of the disorder. The e-e interaction suppresses the relaxation through the enhancement of the magnetic-field-induced spin splitting of the Landau level.