It is shown that a small magnetic field alternating at audio frequencies causes an amplitude modulation of the electric field associated with the flux motion oscillating at microwave frequencies in superconducting thin films. The phase of the modulation component of this electric field can be changed almost 180° by reversing the sweep of the external magnetic field. These phenomena can be explained by invoking the influence of boundary currents on the motion of the flux lattice.

• Received 5 November 1971

DOI:https://doi.org/10.1103/PhysRevB.6.887