D.R. Leadley and R.J. Nicholas
Department of Physics, Clarendon Laboratory, Parks Road, Oxford, OX1
3PU, UK
J.J. Harris
Semiconductor IRC, Imperial College, London. SW7 2BZ
C.T. Foxon
Department of Physics, The University, Nottingham, NG7 2RD, UK
In high quality GaAs-GaAlAs heterojunctions the mobility may change by factors of ~500 between 1K and 300K, however in contrast to classical expectations there is a large magneto- resistance, which varies with impurity and electron density, in a similar way to the mobility at low temperature. Provided kT< hwc it is temperature independent which shows impurity scattering to be dominant in high field. Once kT> hwc inter-Landau level transitions are allowed and optic phonon scattering dominates. On top of this background are oscillations due to magnetophonon resonance. In very high mobility samples they disappear unexpectedly at high fields (rather than increasing with B), suggesting the scattering is predominantly by intra-Landau level processes.
Presented at: Institute of Physics, Condensed Matter and Materials Physics Conference, Birmingham, 1991