Magnetic-field-induced resonant tunneling in parallel two-dimensional systems

The magnetoresistance at 4.2 K of two spatially remote two-dimensional electron gases is investigated. The magnetic field B is applied parallel to the planes of the two-dimensional electron gases (2DEG's). Tunneling between them occurs above a critical field Bc. In a configuration where the current I is perpendicular to B, a resistance resonance is observed at Bc, which is absent when I is parallel to B. This resistance resonance is due to a large difference in the mobilities of the two 2DEG's. A model calculation based on the Boltzmann equation and the symmetry properties of the electron subband dispersion curves reproduces the observed phenomena.