Quantum Hall ferromagnetism in a two-dimensional electron system

Experiments on a nearly spin degenerate two-dimensional electron system rev eals unusual hysteretic and relaxational transport in the fractional quantu m Hall effect regime. The transition between the spin-polarized (with fill fraction nu = 1/3) and spin-unpolarized (nu = 2/5) states is accompanied by a complicated series of hysteresis. loops reminiscent of a classical, ferr omagnet, In correlation with the hysteresis, magnetoresistance can either g row or decay Logarithmically in time with remarkable persistence and does n ot saturate. In contrast to the established models of relaxation, the relax ation rate exhibits an anomalous divergence as temperature is reduced. Thes e results indicate the presence of novel two-dimensional ferromagnetism wit h a complicated magnetic domain dynamic.