Magnetization, flux creep and transport in Tl-Ca-Ba-Cu-O thin films
Static magnetization, flux creep, and electrical transport data are presented for thin films in the high-temperature superconducting Tl-Ca-Ba-Cu-O system. Unoriented polycrystalline 0.7 ..mu..m-thick films of both Tl-2223 and Tl-2122 were prepared by sequential e-beam evaporation onto yttria-stabilized cubic zirconia and strontium titanate followed by careful post-deposition anneals. Low-field diamagnetic shielding shows very large demagnetization normal to the film, arising from current flow over macroscopic in-plane distances. Above 50 K there is negligible magnetization hysteresis consistent with easy flux motion. The magnetization exhibits a logarithmic time dependence due to activated flux creep with a small pinning energy of 0.083 eV. The transport properties are very different from those of polycrystalline YBa/sub 2/Cu/sub 3/O/sub 7-delta/ (Y-123) films. Tl-2223 films have shown critical current densities up to 240,000 A/cm/sup 2/ at 76 K (110,000 A/cm/sup 2/ for Tl-2122 films) with low sensitivity to in-plane magnetic fields and moderate sensitivity to perpendicular fields. This anisotropic behavior indicates that grain boundary Josephson junctions are not dominating the transport. The strong intergranular links and high critical current densities show the potential of these polycrystalline thin films for applications. 26 refs., 6 figs.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 6550959
- Report Number(s):
- SAND-88-2858C; CONF-881127-3; ON: DE89005236
- Country of Publication:
- United States
- Language:
- English
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75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BEAMS
CHALCOGENIDES
CREEP
CRITICAL CURRENT
CRITICAL TEMPERATURE
CURRENT DENSITY
CURRENTS
ELECTRIC CURRENTS
ELECTRON BEAMS
FILMS
LEPTON BEAMS
MAGNETIC FIELDS
MAGNETIZATION
MECHANICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PARTICLE BEAMS
PHYSICAL PROPERTIES
SUPERCONDUCTING FILMS
TEMPERATURE DEPENDENCE
THALLIUM COMPOUNDS
THALLIUM OXIDES
THERMODYNAMIC PROPERTIES
THIN FILMS
TRANSITION TEMPERATURE
TRANSPORT THEORY