Quenching of the Hall resistance in ballistic microstructures: A collimation effect

We present both calculations and a physical interpretation of the observed suppression (quenching) of the low-field Hall resistance in quasi-one-dimensional ballistic microstructures. We find that quenching is due to a property of the contact geometry and is not intrinsic to the quasi-one-dimensional limit. Generic quenching, as observed experimentally, is found only when the width of the wires is gradually increased near the junction to the Hall probes. The resulting collimation of the electrons in the forward direction reduces the sensitivity to a magnetic field.