Magnetic anticrossing of 1D subbands in ballistic double quantum wires

We study the low-temperature in-plane magnetoconductance of vertically coup led double quantum wires. Using a novel flip-chip technique, the wires are defined by two pairs of mutually aligned split gates on opposite sides of a less than or equal to 1 micron thick AlGaAs/GaAs double quantum well heter ostructure. We observe quantized conductance steps due to each quantum well and demonstrate independent control of each 1D wire. A broad dip in the ma gnetoconductance at similar to 6 T is observed when a magnetic field is app lied perpendicular to both the current and growth directions. This conducta nce dip is observed only when 1D subbands are populated in both the top and bottom constrictions. This data is consistent with a counting model whereb y the number of subbands crossing the Fermi level changes with field due to the formation of an anticrossing in each pair of 1D subbands. (C) 2000 Aca demic Press.