In a dilute two-dimensional hole gas located at a Si/SiGe heterojunction we have investigated the variation of magnetoresistance and Hall resistance with tilting of magnetic field. The only pronounced effect of the longitudinal component of field is a strong increase of the magnetoresistance in the insulating state located between the quantum-Hall-effect states with filling factors 1 and 3. The Hall resistance in the insulating state was found to be insensitive to the longitudinal field. A model is proposed that explains the appearance of an insulating state interrupted by the quantum-Hall-effect states. It describes a strong dependence of the insulating state width on the ratio of the Zeeman splitting and cyclotron energies. It is shown that the latter effect might be responsible for our observations.

• Received 10 May 1995

DOI:https://doi.org/10.1103/PhysRevB.52.R11638