DIAMAGNETIC SDH EFFECT IN CROSSED AND PARALLEL CURRENT MAGNETIC-FIELDDIRECTIONS IN SI-DELTA-DOPED GAAS

We have performed magnetoresistance measurements on Si-delta-doped GaA s in parallel pulsed magnetic fields up to 50 T. A systematic study ha s been made in order to understand the influence of the direction betw een the in-plane magnetic field and the sample current on the magnetor esistance. The parallel held magnetoresistance traces of thin Si-delta -doped GaAs layers ( < 20 Angstrom) show a distinct difference in the depopulation of the n = 1 subband when the magnetic field is either pa rallel or perpendicular to the sample current. For this subband, the m agnetic field values at depopulation deviate significantly from the un iversal depopulation curves calculated by Reisinger and Koch.