Magnetic field anti-symmetry of photovoltaic voltage in evanescent   microwave fields
  A two dimensional electron system without spatial inversion symmetry develops a sample specific dc voltage when exposed to a microwave radiation at low temperature. We investigate this photovoltaic (PV) effect, in the case where spatial symmetry is broken by an evanescent high-frequency potential. We measure the induced PV voltage in a ${\rm GaAs/Ga_{1-x}Al_{x}As}$ Hall bar at magnetic fields in the Tesla range. We find that in this regime the induced PV voltage is anti-symmetric with magnetic field, and exhibits regular Shubnikov-de Haas like oscillations. Our experimental results can be understood from a simple model, which describes the effect of stationary orbital currents caused by microwave driving. 
A. Chepelianskii, S. Gu\'eron, F. Pierre, A. Cavanna, B. Etienne and   H. Bouchiat