Landau levels in two and three-dimensional electron gases in a wide parabolic quantum well

Shubnikov-de Haas oscillations are measured in a wide parabolic quantum well with 6 subbands in a tilted magnetic fi eld. We find two types of oscillations. The oscillations at low magnetic field are shifted towards higher fields with tilted angles, and can be attributed to the two-dimensional Landau state at the bottom subband. The position of the second type oscillations do not shift with tilted angles indicating a three-dimensional character of the Landau state formed by the highest subbands. The bottom level in the quantum well is not overlapped with the highest subbands due to the enhanced quantum scattering time of the lowest subbands