Title :
Jc(H) crossover in YBCO thick films and Bi2223/Ag tapes with columnar defects
Author :
Li, Qiang ; Suenaga, M. ; Foltyn, S.R. ; Wang, H.
Author_Institution :
Mater. Sci. Dept., Brookhaven Nat. Lab., Upton, NY, USA
fDate :
6/1/2005 12:00:00 AM
Abstract :
We report a study of critical current density Jc as a function of temperature T, magnetic field H, and film thickness d in a series of high quality YBa2Cu3O7-δ (YBCO) films. A crossover in the thickness dependence of Jc(H) curves was observed for T>50 K, where thinner film carries significantly lower Jc(H) than thicker film at high fields, while the opposite was observed at low fields. This Jc(H) crossover behavior seems to be a general feature for a superconducting system with a spectrum of pinning density, whose trend opposes to the effective volume faction for Jc. This generalization is supported by examining Jc(H) crossover behaviors observed earlier in the Bi2Sr2Ca2Cu3O10+δ(Bi2223)/Ag tapes irradiated with 5.8 GeV Pb ions, where enhanced Jc(H) at high fields is attributed to the density increase in the columnar flux pinning centers.
Keywords :
barium compounds; bismuth compounds; calcium compounds; critical current density (superconductivity); flux pinning; lead compounds; silver; strontium compounds; superconducting tapes; yttrium compounds; Bi2PbSr2Ca2Cu3O10-Ag; Jc(H) crossover; YBCO coated conductors; YBCO thick films; YBa2Cu3O7; columnar defects; columnar flux pinning centers; critical current density; film thickness; magnetic field; pinning density; superconducting system; thickness dependence; volume faction; Conductive films; Conductors; Crystallization; Flux pinning; High temperature superconductors; Magnetic films; Substrates; Superconducting films; Thick films; Yttrium barium copper oxide; Columnar defects; YBCO coated conductors; critical current; flux pinning;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
DOI :
10.1109/TASC.2005.848213
