NEGATIVE HOPPING MAGNETORESISTANCE OF 2-DIMENSIONAL ELECTRON-GAS IN A SMOOTH RANDOM POTENTIAL

We show that the tunnel coupling between semiclassical states localized in different minima of a smooth random potential increases when magnetic field is applied. This increase originates from the difference in gauge factors which electron wave functions belonging to different electron "lakes" acquire in the presence of the field. In the common case of a narrow barrier between two lakes, the characteristic magnetic field is determined by the area of the lakes, and thus may be quite small. The effect of the field on coupling constants leads to a negative magnetoresistance in low-temperature conduction. © 1995 The American Physical Society.