Anisotropic transport properties of BSCCO single crystals and Ag-clad tapes in high magnetic fields
We report measurements of resistivity and critical current density on single crystals of Bi-2212 with current flow both parallel and perpendicular to the CuO2 planes and in magnetic fields to 18T. For comparison, similar measurements were performed on samples of Bi-2223 tape conductors with the Ag cladding removed. For current flow along the c-axis of the crystals the semiconducting behavior (resistivity increasing with decreasing temperature) is extended to below 50K in a field of 18T, followed by a sharp transition to the superconducting state. From I-V curves of c-axis transport we extract the magnetic field and temperature dependencies of the interlayer critical current density Jc,c and define a decoupling line HD(T) above which Jc,c vanishes. HD(T) lies close to but above the irreversibility Hirr(T) obtained from magnetic measurements. We also observe a decoupling induced below HD(T) by the application of a magnetic field starting from the zero field cooled state, ZFC. The resulting ''pancake vortex'' density gradient causes a loss of c-axis phase coherence and produces a c-axis resistance that relaxes logarithmically with time as the magnetization decays. These results are contrasted with similar measurements performed on highly textured Bi-2223 tapes. For current flow along the tape normal (nominal c-axis) the resistivity is metallic and its temperature and field dependence scales with those for in-plane current flow. Similarly critical currents for the two directions show similar field and orientation dependence. These results are consistent with predominant percolative current paths along crystallographic ab planes even for transport normal to the tape plane.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 10188134
- Report Number(s):
- LA-UR-94-3235; CONF-940926-2; ON: DE95000938; TRN: 94:009260
- Resource Relation:
- Conference: 7. conference on superconductivity and applications, Buffalo, NY (United States), 7-9 Sep 1994; Other Information: PBD: [1994]
- Country of Publication:
- United States
- Language:
- English
Similar Records
Effects of splayed columnar defects produced by heavy fission fragments on vortex dynamics in BSCCO conductors
Transport and magnetization currents in BSCCO/Ag tapes