Radio frequency vortex dynamics in heavy ion irradiated (Bi-Pb)₂Sr₂Ca₂Cu₃O₁₀ superconducting platelets

Abstract

We report measurements of vortex dynamics in heavy ion irradiated (Bi-Pb)₂Sr₂Ca₂Cu₃O₁₀ superconducting tapes in the high-temperature (T≥60 K) and low-field (μ0H lt;0.3 T) regimes. The temperature, magnetic field strength and angular dependences of radio-frequency (RF) penetration depth λ(H, T) are measured and compared with the behavior of unirradiated samples. The pinning force constant, k_p, and viscosity coefficient η are extracted from the field dependence of λ(H, T). The angular dependence of the RF penetration depth in samples irradiated at the field equivalent fluence of 0.5 and 3.0 T is minimum when the external field is brought into alignment with the columnar defects (CDs). While this characteristic feature of anisotropic pinning due to CDs disappear in a temperature regime where J_c is high, in the vortex liquid state closer to T_c, this feature grows with the increasing field strength. The overall changes in η, k_p and the angular dependence of λ(H, T) are discussed in the framework of the Bose glass theory for vortex dynamics in highly layered superconductors.