Magnetic field and temperature dependence of thermally activated dissipation in epitaxial thin films of YBa2(Cu1-x Zn-x)3O(7-d)

The scaling behavior of the effective activation energy of high-quality epi taxial c-oriented YBa2(Cu1-xZnx)(3)O7-d thin films has been studied as a fu nction of temperature and magnetic field. For all samples, the effective ac tivation energy scales as U(T,H-mu0) = U-0(1 - T/T-c)H-m(n) with exponent m = 1.6 +/- 0.02 - 1.3 +/- 0.02 and the field scaling 1/H-mu0 and -ln(mu0)H for thick films and ultrathin films, respectively. The results are discusse d taking account of the influence of the Zn substitution on the flux pinnin g in epitaxial YBa2(Cu1-xZnX)(3)O7-d thin films.