Reentrant ν=1 quantum Hall state in a two-dimensional hole system

We report the observation of a reentrant quantum Hall state at the Landau level filling factor ν=1 in a two-dimensional hole system confined to a 35-nm-wide (001) GaAs quantum well. The reentrant behavior is characterized by a weakening and eventual collapse of the ν=1 quantum Hall state in the presence of a parallel magnetic field component _B, followed by a strengthening and reemergence as _B is further increased. The robustness of the ν=1 quantum Hall state during the transition depends strongly on the charge distribution symmetry of the quantum well, while the magnitude of _B needed to invoke the transition increases with the total density of the system.