Anisotropic magnetotransport in weakly coupled GaAs-AlxGa1-xAs multiple quantum wells

We have studied for the first time the effect of an applied magnetic field on the tunneling current flowing perpendicular to a weakly coupled multiple-quantum-well structure. Due to the two-dimensional density of states of the electron gas in each well, tunneling among the wells occurs only when the states in the adjacent wells are nearly degenerate. An applied magnetic field parallel to the superlattice removes the degeneracy and leads to a variety of striking phenomena in the current-voltage characteristics. In strong contrast to this, when the magnetic field is perpendicular to the superlattice, the degeneracy is preserved and there is no significant change in the characteristics.