Acoustoelectric pumping through a ballistic point contact in the presence of magnetic fields

The acoustoelectric current J induced in a ballistic point contact (PC) by a surface acoustic wave is calculated in the presence of a perpendicular magnetic field B. It is found that the dependence of the current on the Fermi energy in the terminals is strongly correlated with that of the PC conductance: J is small at the conductance plateaus and is large at the steps. Like the conductance, the acoustoelectric current has the same functional behavior as in the absence of a field, but with renormalized energy scales, which depend on the strength of the magnetic field B.