HARMONIC AC SUSCEPTIBILITIES FOR TEXTURED YBA2CU3O7

Citation
Y. Ge et al., HARMONIC AC SUSCEPTIBILITIES FOR TEXTURED YBA2CU3O7, Physica. C, Superconductivity, 292(1-2), 1997, pp. 59-64
Citations number
30
ISSN journal
09214534
Volume
292
Issue
1-2
Year of publication
1997
Pages
59 - 64
Database
ISI
SICI code
0921-4534(1997)292:1-2<59:HASFTY>2.0.ZU;2-7
Abstract
Harmonic ac susceptibilities were measured as a function of temperatur e (T), ac field frequency (f) and amplitude (B-ac,), and de field (B-d c,) for bulk textured YBa2Cu3O7. The higher harmonics consist mainly o f odd ones in strong de fields (B-dc, > 50 mT) and depend on B-dc, B-a c, and f. It is confirmed that the origin of harmonic generation for t he textured sample is thermally activated flux diffusion over barriers Ci which depend nonlinearly on current density (j). The high nonlinea r flux diffusion induces a self-organized Bean critical state in which the straight line approximation is a good description of the field pr ofile except that the current density is j(f) instead of the critical value j(c). Thus the frequency dependent Bean critical state accounts for the origin of harmonic generation and explains the present and oth er experiments well. (C) 1997 Elsevier Science B.V.