  Magnetotransport properties are investigated for a high mobility Si two
dimensional electron systems in the vicinity of a Landau level crossing point.
At low temperatures, the resistance peak having a strong anisotropy shows large
hysteresis which is attributed to Ising quantum Hall ferromagnetism. The peak
is split into two peaks in the paramagnetic regime. A mean field calculation
for the peak positions indicates that electron scattering is strong when the
pseudospin is partially polarized. We also study the current-voltage
characteristics which exhibit a wide voltage plateau.
