We report the response of amorphous dielectrics to large dc electric fields E. Upon the rapid application of the field, the ac susceptibility ${\varepsilon }^{\prime }$ increases abruptly and then decays logarithmically for $t-t_0\approx 1$ to ${10}^5$ sec. Slow dc field sweeps show a minimum in ${\varepsilon }^{\prime }$ at the field present when the sample was cooled from 300 K. If E is held fixed at a different value, a second local minimum in ${\varepsilon }^{\prime }$ develops at that field, evident upon subsequent dc field sweeps. We present the temperature, frequency, and amplitude dependences of these related phenomena and discuss possible origins.

• Received 14 February 1994

DOI:https://doi.org/10.1103/PhysRevLett.73.268