QUANTUM-THEORY OF HALL ANOMALIES AND BEND RESISTANCE IN NARROW BALLISTIC CONDUCTORS AT LOW MAGNETIC-FIELDS

A theory of the four-terminal resistances of flared ballistic quantum wire junctions in the few-mode regime is presented. Adiabatic collimation and reflection of electrons in the flared regions, and non-adiabatic mode-mixing in the junction core result in resonant electron trapping and quantum interference. At low T, RH is coherently quenched, enhanced or negative at low B, depending sensitively on EF and junction geometry. At higher T, suppression of phase coherence results in behavior strikingly similar to that observed in the many-mode regime, despite the inapplicability of classical arguments. © 1990.