Electronic Resource
[S.l.]
:
American Institute of Physics (AIP)
Journal of Applied Physics
64 (1988), S. 5800-5802
ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Nonresonant microwave (MW) absorption is observed at the surface of high-Tc superconducting oxides in the presence of a static magnetic field and a scanning field. Nonlinear signals are obtained that show absorption troughs at the endpoints of the field scan superimposed on a hysteretic variation in absorption with field. The model of Portis et al. accounts quantitatively for the detailed shape of the observed signals. It enables the direct measurement of a critical field H*=(4π/c)Jcλ which depends on the critical current Jc and the static field penetration depth λ. In addition, the ratio λMW/λ is deduced from the shape of the troughs, with λMW the penetration depth of the MW fields. Typical values are H*(approximately-equal-to)5 μT and λMW(approximately-equal-to)3λ for a sintered YBaCuO sample at 77 K, and nearly the same H* but λMW(approximately-equal-to)λ at 4.2 K. Since the observed shapes also depend on the previous slow changes of the applied field, these investigations account for the memory effect observed with the usual resonance techniques.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.342209
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