Magnetic-field asymmetry of nonlinear mesoscopic transport in channels coupled to a single metallic gate

The nonlinear transport of asymmetric quantum wires has been studied under the influence of an external magnetic field. The investigated structures were based on a modulation doped GaAs/AlGaAs heterostructure with a two-dimensional electron gas approximately 80 nm below the surface. The in-plane asymmetry of the quantum wire was realized by two different side walls, one defined via an etched channel and the other by a metallic top gate. Magnetic fields were applied perpendicular to the sample surface. The conductance of the quantum wires was studied at a temperature of 4.2 K. It was found that such asymmetric quantum wires show a pronounced magnetic-field asymmetry, defined as the change in the conductance induced by a change in the magnetic-field sign. The asymmetric conductance increases linearly with the bias voltage. These findings could be explained by a magnetic-field asymmetry of nonlinear mesoscopic transport.