ELECTRON-ELECTRON INTERACTIONS AND SPONTANEOUS SPIN POLARIZATION IN QUANTUM HALL EDGE STATES

We study the effects of electron-electron interactions on the ground s tate of integral quantum Hall edge states in the Hartree-Fock approxim ation. We find that, in the absence or Zeeman splitting, the outermost edge state undergoes a spontaneous transition between spin-unpolarize d and spin-polarized ground states at a sample-dependent critical valu e of the bulk filling v(bulk)c approximately 4. The abrupt appearance, in the spin-polarized state, of a sizable (about a magnetic length) s eparation between edge states of opposite spin should make the transit ion accessible to a range of magnetotransport experiments.