Nonlinearities in the Hall resistance by retroreflective scattering

Nonlinearities in the classical Hall resistance of two-dimensional electron gases exposed to retroreflective obstacles at random positions are reported. The Hall slope develops a nonmonotonic component which increases strongly in amplitude and shifts to larger magnetic fields as the obstacle density increases. At small magnetic fields, the relation between the longitudinal and transverse conductivity remains in qualitative agreement with the Drude-Hall equations, although the characteristic time scale can be no longer interpreted as a momentum relaxation time. The corresponding Hall conductivity develops a marked minimum at a characteristic magnetic field outside the interval where the data agree qualitatively with the Drude-Boltzmann model. With the help of simulations based on the Kubo model, this minimum is attributed to successive retroreflections which lead to inverted transverse deflection.