Peak effect at microwave frequencies in swift heavy ion irradiated YBa2Cu3O7-e??? thin ???lms

摘要

The vortex dynamics at microwave frequencies in YBa2Cu3O7-e??? (YBCO) ???lms have been studied. We observe a peak in the microwave (4.88 and 9.55 GHz) surface resistance in some ???lms in magnetic ???elds up to 0.8 T. This is associated with the `peak-effecta€? phenomenon and re???ects the ordera€“disorder transformation of the ???ux line lattice near the transition temperature. Introduction of arti???cial pinning centers like columnar defects created as a result of irradiation with 200 MeV Ag ion (at a ???uence of 4 ?— 1010 ions/cm2) leads to the suppression of the peak in ???lms previously exhibiting `peak effecta€?.