Radio frequency vortex dynamics in heavy ion irradiated (Bi-Pb)2ST2Ca2Cu3O10 superconducting platelets

We report measurements of vortex dynamics in heavy ion irradiated (Bi-Pb)(2)Sr2Ca2Cu3O10 superconducting tapes in the high-temperature (T greater than or equal to 60 K) and low-field (mu H-0 < 0.3 T) regimes. The temperature, magnetic field strength and angular dependences of radio-frequency (RF) penetration depth lambda (H, T) are measured and compared with the behavior of unirradiated samples. The pinning force constant, k(p), and viscosity coefficient eta are extracted from the field dependence of lambda (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 eta, k(p) and the angular dependence of lambda (H, T) are discussed in the framework of the Bose glass theory for vortex dynamics in highly layered superconductors, (C) 2001 Published by Elsevier Science Ltd. All rights reserved.