Magnetoresistance of one-dimensional subbands in tunnel-coupled double quantum wires

We study the low-temperature in-plane magnetoresistance of tunnel-coupled q uasi-one-dimensional quantum wires. The wires are defined by two pairs of m utually aligned split gates on opposite sides of a less than or equal to 1- mu m-thick AlxGa1-xAs/GaAs double-quantum-well heterostructure, allowing in dependent control of the width of each quantum well. In the ballistic regim e, when both wires are defined and the field is perpendicular to the curren t, a large resistance peak at similar to 6 T is observed with a strong gate voltage dependence. The data are consistent with a counting model whereby the number of subbands crossing the Fermi level changes with field due to t he formation of an anticrossing in each pair of one-dimensional subbands. [ S0163-1829(99)00540-8].