Determination of the phase of magneto-intersubband scattering oscillationsin heterojunctions and quantum wells

The oscillatory magnetoresistance of a two-dimensional electron system with two occupied subbands has been studied in an Al0.3Ga0.7As/GaAs heterojunct ion and an Al0.3Ga0.7As/In0.15Ga0.85As/GaAs quantum well between 4 and 100 It. As a consequence of the second populated subband, a magneto-intersubban d scattering effect is observed at low-magnetic fields in addition to the S hubnikov-de Hails effect. Due to the different temperature damping of the t wo effects, the oscillatory magnetoresistance can exhibit both effects simu ltaneously at high and respectively low fields. Using the extrema positions , it is possible to clearly identify a theoretically predicted phase differ ence between the Shubnikov-de Haas and the magneto-intersubband scattering oscillations at temperatures higher than 4 K. This phase difference influen ces the power spectrum of reciprocal-field magnetoresistance data. [S0163-1 829(98)04444-0].