DocumentCode :
1101975
Title :
Frequency dependence of AC susceptibility due to the viscous motion of flux lines
Author :
Takacs, S. ; Gömöry, F. ; Lobotka, P.
Author_Institution :
Inst. of Electr. Eng., Slovak Acad. of Sci., Bratislava, Czechoslovakia
Volume :
27
Issue :
2
fYear :
1991
fDate :
3/1/1991 12:00:00 AM
Firstpage :
1057
Lastpage :
1060
Abstract :
The authors studied the influence of viscous flux flow on the field distribution and hysteresis losses in high-Tc superconductors with field-dependent critical current density J c. The results are compared with measurements of AC susceptibility on ceramic YBaCuO and BiSrCaCuO as well as on single-crystal YBaCuO samples. Clear evidence for flux flow effects is seen for frequencies above approximately 1 kHz for all samples. The extreme flux flow model indicates that the flux flow should play an important role at much lower frequencies. The deviations from these results could be caused to some extent by the field dependence of J c, but at lower frequencies the flux creep seems to be dominant. This is confirmed by the current-voltage characteristics of analogous samples. It is shown that some important differences appear in the frequency dependences of the real and imaginary parts of the AC susceptibility for fields of harmonic and triangular shape. These differences, as well as the weaker flux flow effects in BiSrCaCuO as compared with YBaCuO, offer support for the conclusion that the flux flow effects are generally less important than supposed by some theories
Keywords :
barium compounds; bismuth compounds; calcium compounds; critical current density (superconductivity); flux creep; flux flow; high-temperature superconductors; magnetic hysteresis; magnetic susceptibility; strontium compounds; yttrium compounds; AC susceptibility; BiSrCaCuO; YBaCuO; ceramic; current-voltage characteristics; field distribution; field-dependent critical current density; flux creep; frequency dependences; high temperature superconductivity; hysteresis losses; single-crystal; viscous flux flow; Critical current density; Current measurement; Density measurement; Fluid flow measurement; Force measurement; Frequency dependence; High temperature superconductors; Hysteresis; Lattices; Yttrium barium copper oxide;
fLanguage :
English
Journal_Title :
Magnetics, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9464
Type :
jour
DOI :
10.1109/20.133361
Filename :
133361
Link To Document :
بازگشت