Disentangled vortex liquid phase in BSCCO-2212 single crystal highly overdoped with oxygen

The in-plane and out-of-plane resistivities of a BSCCO-2212 single crystal highly overdoped with oxygen have been measured in an external magnetic fie ld ranging from 100 Oe to 40 kOe and applied parallel to c-axis. The data i ndicate a gradual solid-liquid transition of the vortex signifying addition al enhancement of disorder in the vortex system. The experimental result al so exhibits a large reduction of anisotropy and reveals the occurrence of v ortex line disentanglement in its liquid phase, implying the presence of lo ngitudinal vortex line ordering characterized by a longitudinal superconduc tivity transition.