Magneto-transport study of Landau level broadening in a gated AlGaAs/GaAs parabolic quantum well structure

We study the Landau level broadening by analyzing the Shubnikov-de Haas oscillations in a gated AlGaAs/GaAs parabolic quantum well structure when only one electronic subband is occupied. Small-angle scattering is determined to be important in this system. The Shubnikov-de Haas oscillations are described equally well by employing Gaussian or Lorentzian broadening of the Landau levels at low magnetic field where the quantum localization effect is not important. A possible explanation is that the electron-electron interactions lead to the overlapping of adjacent Landau levels and one can not distinguish between the two broadening types.