Low-temperature vortex dynamics in (Bi,Pb)2212 single crystals with columnar defects aligned at 45 degrees to the c-axis

摘要

The focus of the present report is the comparison of pinning properties between a Bi1.8Pb0.2Sr2CaCu2O8+delta single crystal irradiated at 45degrees and the one irradiated along c-axis. At temperatures T greater than or equal to 40K, and in the vortex solid state, angular measurements reveal for both samples a pronounced dip in the dissipation when a magnetic field is applied parallel to the tracks. In contrast, at low temperature the dip shifts from inclined columnar defects towards the c-axis direction. The dip shift observed with decreasing T can be associated to a partially pinned staircase vortex structure. (C) 2004 Elsevier B.V. All rights reserved.