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 $B_c$. In a configuration where the current $I$ is perpendicular to $B$, a resistance resonance is observed at $B_c$, 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.