Effect of electron and phonon anisotropy on the phonon-drag thermopower of a classical two-dimensional electron gas in a magnetic field

The standard theory of the phonon-drag thermopower tensor (S) over cap for a classical two-dimensional electron gas in a perpendicular magnetic field B describes fairly well the longitudinal tensor element S-yx(g). However, the transverse tensor element S-yx(g) is only similar to 0.5% of what is measured in a GaAs/AlGaAs quantum well. This large error fan be removed when B < 3 T by allowing for the simultaneous presence of electron and phonon anisotropy. The restriction on B is introduced only to gain physical insight. Similar results ars expected when S-yx(g) becomes nonlinear in B and in the Landau quantization regime. [S0031-9007(98)05402-7].