CORRELATIONS, INHOMOGENEOUS SCREENING, AND SUPPRESSION OF SPIN SPLITTING IN QUANTUM WIRES AT STRONG MAGNETIC-FIELDS

A self-consistent treatment of exchange and correlations in a quantum wire (QW) subject to a strong perpendicular magnetic field is presente d using a modified local-density approximation. The influence of many- body interactions on the spin splitting between the two lowest Landau levels (LL's) is calculated within the screened Hartree-Fock approxima tion, for filling factor v=1, and the strong spatial dependence of the screening properties of electrons is taken into account. In compariso n with the Hartree-Fock result, the spatial behavior of the occupied L L in a QW is strongly modified when correlations are included. Correla tions caused by screening at the edges strongly suppress the exchange splitting and smoothen the energy dispersion at the edges. The theory accounts well for the experimentally observed strong suppression of th e spin splitting pertinent to the v=1 quantum Hall effect state as wel l as the destruction of this state in long, quasiballistic GaxAl1-xAs/ GaAs QW's.