Electron-electron interactions and spontaneous spin polarization in quantum Hall edge states

We study the effects of electron-electron interactions on the ground state of integral quantum Hall edge states in the Hartree-Fock approximation. We find that, in the absence of Zeeman splitting, the outermost edge state undergoes a spontaneous transition between spin-unpolarized and spin-polarized ground states at a sample-dependent critical value of the bulk filling νbulkᶜ{~}4. The abrupt appearance, in the spin-polarized state, of a sizable (about a magnetic length) separation between edge states of opposite spin should make the transition accessible to a range of magnetotransport experiments.