Dissipation in the superconducting mixed state in the presence of a small oscillatory magnetic-field component

We have studied the electric resistivity in superconducting amorphous (Formula presented)Si films in a perpendicular magnetic field (Formula presented)+(Formula presented) sin ωt with (Formula presented)≪(Formula presented). For (Formula presented)=0 a resistive voltage only appeared due to flux creep above the critical current (Formula presented). For (Formula presented)>0 we observed perfectly Ohmic behavior at currents I≪(Formula presented)n((Formula presented)=0), with the resistivity increasing proportional to ω and (Formula presented). We present a simplified model discussion explaining our results in terms of the magnetic flux transferred across the sample during each cycle of the oscillatory magnetic field because of the electric transport current. © 1997 The American Physical Society.