Peak effect in laser ablated DyBa2Cu3O7-delta films at microwave frequencies at subcritical currents

In this article we report the observation of a peak in the microwave surfac e resistance (at frequencies similar to 10 GHz) of laser ablated DyBa2Cu3O7 - delta films in magnetic field ranging from 2 to 9 kOe (parallel toc) clo se to the superconducting transition temperature [T-c(H)]. The exact nature of the peak is sample dependent but it follows a general behavior. The pea k shifts to lower temperature when the magnetic field is increased. It has strong frequency dependence and the peak is pronounced at frequencies close to the depinning frequency of the flux line lattice. From the observed tem perature and field dependence we argue that this peak is associated with th e order-disorder transition of the flux line lattice close to T-c(H). (C) 2 001 American Institute of Physics.