  Anisotropic charge transport is observed in a two-dimensional (2D) hole
system in a perpendicular magnetic field at filling factors nu=7/2, nu=11/2,
and nu=13/2 at low temperature. In stark contrast, the transport at nu=9/2 is
isotropic for all temperatures. Isotropic hole transport at nu=7/2 is restored
for sufficiently low 2D densities or an asymmetric confining potential. The
density and symmetry dependences of the observed anisotropies suggest that
strong spin-orbit coupling in the hole system contributes to the unusual
transport behavior.
