INDIRECT EXCHANGE COUPLING OF NUCLEAR SPINS OF MAGNETIC IMPURITIES IN 2D ELECTRON SYSTEM

Abstract

The indirect exchange interaction between two magnetic impurities in a two-dimensional electron system under a strong magnetic field is studied. The nuclear spin coupling is mediated by Landau electrons bound to these impurities. We consider the contact hyperfine coupling of the bound Landau electrons, which is an s-type wave function and is therefore significant. The d electrons are indirectly involved in the contact interaction through their resonance scattering potential, which is found to be spin selective and therefore binds Landau electrons with proper spin polarization. Thus, the resulting superexchange interaction between two different sites involves the bound Landau states of one site and the impurity d states of the second site, resulting in an antiferromagnetic interaction between the nuclear spins of the impurities. The coupling constant between these nuclear spins, J, is found to depend strongly on the ratio of the impurity separation over the magnetic length. Possible applications of these results may include a long-range mechanism for coupling between two nuclear spins to be used as a qubit interaction with a spacing distance of the order of magnitude of the magnetic length.