Antiscreening and exchange-enhanced spin splitting in quantum wires

Theoretical work is presented, suggesting that in regimes of experimental interest, the exchange enhancement of the spin splitting of Landau levels in quantum wires as evidenced in their two-terminal conductance is increased by the confinement. This is due to an effect in which electron-electron interactions are strengthened by interaction with polarizable edge-state charge. This antiscreening effect is confirmed by calculating exchange enhancement in a quasi-one-dimensional conductor in the ‘‘screened’’ Hartree-Fock approximation. Preliminary experimental evidence for the effect is also presented.