Radio frequency vortex dynamics in heavy ion irradiated (Bi-Pb)(2)ST2Ca2Cu3O10 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) pe netration depth lambda (H, T) are measured and compared with the behavior o f unirradiated samples. The pinning force constant, k(p), and viscosity coe fficient 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 fie ld is brought into alignment with the columnar defects (CDs), While this ch aracteristic feature of anisotropic pinning due to CDs disappear in a tempe rature 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 layere d superconductors, (C) 2001 Published by Elsevier Science Ltd. All rights r eserved.