High critical current density and its field dependence in mixed rare earth (Nd,Eu,Gd)Ba2Cu3O7−δ thin films

Compared with mono-rare earth 123 films, ternary rare earth (Nd,Eu,Gd)Ba2Cu3O7−δ (NEG123) films show higher critical current density (Jc) and improved irreversibility field (Hirr), but no increase in the characteristic field corresponding to a crossover from a low-field plateau to a linear region in a log Jc–log H plot. At intermediate fields, Jc vs H scales as H(−0.5±0.05) for NEG123, in contrast to H(−0.73±0.05) for mono-rare earth samples such as Gd123. The slow power decay of Jc vs H together with the improved Jc and Hirr strongly implies that extra flux pinning centers exist in NEG123, which are thought to be noncorrelated stress fields induced by lattice mismatch.

[1]  N. Sakai,et al.  Pinning characteristics in chemically modified (Nd, Eu, Gd)–Ba–Cu–O superconductors , 2003 .

[2]  N. Sakai,et al.  New type of vortex pinning structure effective at very high magnetic fields. , 2002, Physical review letters.

[3]  A. Pan,et al.  Vortex matter in superconductors , 2001 .

[4]  I. Ovid’ko.  LETTER TO THE EDITOR: Effects of misfit stresses on high-TC superconductivity in thin-film cuprates , 2001 .

[5]  G. Cuttone,et al.  Control of the critical current density in YBa 2 Cu 3 O 7 − δ films by means of intergrain and intragrain correlated defects , 1999 .

[6]  R. L. Wang,et al.  Evidence for the lattice-mismatch-stress-field induced flux pinning in (Gd1 − xYx)BA2Cu3O7 − σ thin films , 1996 .

[7]  Thompson,et al.  Accommodation of vortices to columnar defects: Evidence for large entropic reduction of vortex localization. , 1996, Physical review. B, Condensed matter.

[8]  Valerii M. Vinokur,et al.  Vortices in high-temperature superconductors , 1994 .

[9]  N. Chen,et al.  Stress-field pinning induced by lattice mismatch in Y-123 superconductors , 1994 .

[10]  Griessen,et al.  Evidence for mean free path fluctuation induced pinning in YBa2Cu3O7 and YBa2Cu4O8 films. , 1994, Physical review letters.

[11]  Nelson,et al.  Boson localization and correlated pinning of superconducting vortex arrays. , 1993, Physical review. B, Condensed matter.

[12]  Schultz,et al.  Angle-resolved critical transport-current density of YBa2Cu3O7- delta thin films and YBa2Cu3O7- delta /PrBa2Cu3O7- delta superlattices containing columnar defects of various orientations. , 1993, Physical review. B, Condensed matter.

[13]  Bernhard Roas,et al.  Off-axis laser deposition of YBa2Cu3O7-δ thin films , 1992 .

[14]  T. Tiefel,et al.  Superconducting properties of YBa2Cu3O7−δ with partial rare earth substitution , 1991 .