  Even denominator fractional quantum Hall states in a ZnO quantum well reveal
interesting phase transitions in a tilted magnetic field. We have analyzed the
planar electron gas in ZnO, confined in a parabolic potential in the third
dimension, perpendicular to the plane of the electron gas. Since the Landau
level gap is very small in this system we have included the screened Coulomb
potential in order to include the effects of all the Landau levels. We observe
an incompressible state - compressible state phase transition induced by the
tilted field. Additionally, the 5/2 state has been experimentally found to be
missing in this system. We however propose that a wider quantum well may help
to stabilize the incompressible phase at the 5/2 filling factor.
