Probing the Fermi surfaces of coupled double quantum wells in the presence of an in-plane magnetic field

Abstract

The anticrossing of the dispersion relations of two two-dimensional electron gases (2DEGs) in an in-plane magnetic field results in distorted Fermi surfaces, leading to density of states and effective mass changes. We have used two different techniques to probe such changes with both the in-plane field and carrier density being systematically altered. The first technique uses a fixed perpendicular field to form Landau levels. By following the evolution of these Landau levels with in-plane field, carrier density and temperature, we are able to determine changes in the subband populations and effective masses. The second technique uses a third conducting layer as a detector of chemical potential changes in the coupled electron gases. This method also allows the determination of effective mass changes in an in-plane field. Calculations of the dispersion curves have been made, illustrating the effect of the parallel field upon subband occupancy and effective mass. These calculations are compared with the experimental data from both methods and are found to be in good agreement.