Magnetotunneling spectroscopy with the field perpendicular to the tunneling direction of the transverse X electrons in GaAs/AlAs double-barrier structures under hydrostatic pressure

We have measured the effect of in-plane magnetic field on tunneling resonances between transverse X states in GaAs/AlAs double-barrier structures under high hydrostatic pressure. Current-voltage and conductance-voltage measurements performed at pressures just beyond the type-II transition, and at fields up to 15 T, reveal clear field dependences of resonances originating from the (Formula presented) and (Formula presented) tunneling processes. Their behavior is consistent with a Lorenz force analysis, and therefore probes the in-plane electron dispersion around the X minima. Differences between measurements with the magnetic field oriented parallel to the [100] and [110] crystal axes reflect the anisotropy of the X minima, a first analysis indicating that the field dependence is dominated by the two (Formula presented) minima with large wave vectors perpendicular to the magnetic-field direction. In support of this, Schrödinger-Poisson modeling of the shift in bias position of the (Formula presented) resonance provides a value for the effective mass parallel to the Lorenz in-plane momentum vector which is consistent with the heavy principal effective mass of the X minima.