In:
Journal of Applied Physics, AIP Publishing, Vol. 95, No. 1 ( 2004-01-01), p. 208-213
Kurzfassung:
The ac losses in three disk-shaped YBa2Cu3O7 (YBCO) films, which were deposited on SrTiO3 by the pulsed-laser-deposition technique and had thicknesses, d, of 0.2, 1.0, and 3.0 μm, were measured in perpendicular applied ac magnetic fields to ∼0.14 T at 10 Hz in liquid nitrogen. The losses at low fields were found to be a strong function of the film thickness. The measured losses were compared with the theoretically calculated losses. The ac losses calculated using a field-independent critical-current density, the Bean model [J. R. Clem and A. Sanchez, Phys. Rev. B 50, 9355 (1994)], agreed very well with the 0.2-μm-thick film, while the calculated losses agreed well with the measured ones when a field-dependent critical-current density, the Kim model [D. V. Shantsev, Y. M. Galperin, and T. H. Johansen, Phys. Rev. B 61, 9699 (2000)] , was used for the films of thickness 1.0 and 3.0 μm. However, a surprising discrepancy was found in the values of Bc and B0 for thinner YBCO films depending on whether they were determined by ac or dc measurements. Bc is defined as Bc=μ0Jc(0)d/2, B0 is the characteristic field in the Kim-model critical-current density JcK(Ba)=Jc(0)/(1+Ba/B0), and Jc(0) is the critical-current density at applied magnetic field Ba=0.
Materialart:
Online-Ressource
ISSN:
0021-8979
,
1089-7550
Sprache:
Englisch
Verlag:
AIP Publishing
Publikationsdatum:
2004
ZDB Id:
220641-9
ZDB Id:
3112-4
ZDB Id:
1476463-5
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