Impurity pinning in epitaxial YBa/sub 2/(Cu/sub 1-x/TM/sub x/)/sub 3/O/sub 7- delta / (TM=Zn, Ni)-thin films

Author

Tome-Rosa, C. ; Schmitt, M. ; Walkenhorst, A. ; Kluge, T. ; Speckmann, M. ; Wagner, P. ; Adrian, H.

Author_Institution

Inst. fur Festkorperphysik, Tech. Hochschule Darmstadt, Germany

Volume

3

Issue

1

fYear

1993

fDate

3/1/1993 12:00:00 AM

Firstpage

1468

Lastpage

1471

Abstract

The dependence of resistive transitions, thermal activation energies, and critical current densities of YBa/sub 2/(Cu/sub 1-x/Zn/sub x/)/sub x/O/sub 7- delta / and YBa/sub 2/(Cu/sub 1-x/Ni/sub x/)/sub 3/O/sub 7-x/- thin films on B, T, and the angle Theta between the magnetic field and the c-axis is studied. A decrease of the critical temperature T/sub c/ with increasing doping concentration x is observed. For small x an increase of the activation energy is found, with a maximum around 0.2%. This can be explained by a model assuming local pinning potentials due to the impurity atoms, which begin to overlap for higher concentrations. The films exhibit higher j/sub c/ values for small dopant concentrations than without doping. If the angle Theta is changed, a different j/sub c/(B, T, Theta ) behavior is found than in high-quality undoped films, with additional structures in the curves.<>

Keywords

barium compounds; critical current density (superconductivity); flux pinning; high-temperature superconductors; superconducting epitaxial layers; superconducting transition temperature; yttrium compounds; YBa/sub 2/(Cu/sub 1-x/Ni/sub x/)/sub 3/O/sub 7-x/; YBa/sub 2/(Cu/sub 1-x/Zn/sub x/)/sub x/O/sub 7- delta /; activation energy; critical current densities; critical temperature; doping concentration; epitaxial thin films; high temperature superconductors; impurity pinning; local pinning potentials; model; resistive transitions; thermal activation energies; Copper; Doping; Impurities; Magnetic field measurement; Magnetic fields; Magnetic films; Rotation measurement; Strontium; Temperature; Zinc;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.233618

Filename

233618