Single-particle relaxation time in a spatially fluctuating magnetic field

We study Shubnikov de Haas (SdH) oscillations in a nonplanar stripe-shaped two-dimensional electron gas (2DEG). The effective-field normal to the nonplanar 2DEG is spatially modulated, when uniform external magnetic field is applied. We find that the amplitude of the SdH oscillations dramatically drops in the tilted magnetic field. From the Dingle plot of SdH oscillations we extract single-particle relaxation time. Reduction of this time in the tilted field, which leads to the enhanced damping of SdH oscillations, is shown to be due to the scattering of the electron by magnetic-field fluctuations. We calculate quantum lifetime of the electron in a tilted magnetic field. The agreement between these calculations and experimental result is found. In order to explain the damping of the SdH oscillations for magnetic field B>1 T we also take into account the spatial variation of the Landau filling factor. [S0163-1829(99)01008-5].