We report the effects of 300 MeV gold ion irradiation on the transition temperature (Tc) and critical current density (Jc) of YBa2Cu3O7epitaxial films. The radiation at a dose as low as 5.6times;1010ions/cm2decreases the zero fieldTcandJc. However, the response of the mixed state in 1ndash;8 T field remains relatively unchanged up to a dose of sim;9times;1010ions/cm2. We argue that the stiffness of the flux lines in a film geometry and the pinning sites distributed at a length scale much smaller than that of the ionhyphen;induced defects are responsible for this null result.
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