Pinning effect on critical dynamics in Tl2Ba2CaCu2O8 films before and after introducing columnar defects

The effect of columnar defects on the critical dynamics of superconducting Tl2Ba2CaCu2O8 (Tl2212) film has been investigated. The Tl-2212 film was irradiated at 0 C by 1.3 GeV U-ions along the normal of the film surface. The dose of 6.0 x 10 ions/cm of the Uion irradiation corresponds to a matching field of 1.2 T. The in-plane longitudinal resistivity of the irradiated Tl2212 has been measured as a function of magnetic field H and temperature T. The extracted fluctuation part of the conductivity σxx(T, H) of the unirradiated sample exhibits 3D-XY scaling behavior that reveals dynamic critical exponent z = 1.8 ± 0.1 and static critical exponent ν ≈ 1.338. The results indicate that the weak interlayer coupling along the c-axis of Tl-2212 significantly influences static critical exponent ν and does not change dynamical critical exponent. After the irradiation, the fluctuation conductivities are enhanced by the strong pinnings and do not exhibit the same 3D-XY scaling behavior as for the unirradiated Tl-2212. Particularly at the low magnetic field values near the matching field of 1.2 T, the fluctuation conductivities show a clear deviation from the critical dynamics, suggesting that the pinning effect on the critical dynamics is significant.