  Spin current perpendicular to the electric current is investigated around
Landau level filling factor $\nu=3$ in a GaAs/AlGaAs two-dimensional electron
system. Measurements of dynamic nuclear polarization in the vicinity of the
edge of a specially designed Hall bar sample indicate that the direction of the
spin current with respect to the Hall electric field reverses its polarity at
$\nu=3$, where the dissipative current carried by holes in the spin up Landau
level is replaced with that by electrons in the spin down Landau level.
