Strongly anisotropic electronic transport at Landau level filling factor nu=9/2 and nu=5/2 under a tilted magnetic field

We have investigated the influence of an increasing in-plane magnetic held on the states of half filling of Landau levels (v = 11/2, 9/2, 7/2, and 5/2 ) of a two-dimensional electron system. In the electrically anisotropic pha se at v = 9/2 and 11/2 an in-plane magnetic held of similar to 1-2 T overco mes its initial pinning to the crystal lattice and reorients this phase. In the initially isotropic phases at v = 5/2 and 7/2 an in-plane magnetic hel d induces a strong electrical anisotropy. In all cases, for high in-plane f ields the high-resistance axis is parallel to the direction of the in-plane field.