CONDUCTANCE MODULATION IN DOUBLE-QUANTUM WELLS DUE TO MAGNETIC-FIELD-INDUCED ANTICROSSING

We observe a strong modulation of the low temperature in-plane conduct ance G(parallel to) of coupled quantum wells (QW's) by an in-plane mag netic field Bit and attribute this to an anticrossing of the two QW di spersion curves. The anticrossing produces a partial energy gap, yield ing large, B-parallel to-tunable distortions in the Fermi surface and density of states. Sweeping B-parallel to moves the energy gap through the Fermi level, with the upper and lower gap edges producing a sharp maximum and minimum in G(parallel to), in agreement with theoretical calculations. The gap energy is directly determined from the data.