An YBCO film as a Josephson medium near T
c
: Frequency and field dependences and scaling relationships |
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Authors: | V A Khokhlov V V Krzhizhanovskii A Yu Prokhorov V F Drobot’ko A V Klimov G G Levchenko |
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Institution: | (1) Donetsk Physicotechnical Institute, National Academy of Sciences of Ukraine, 83114 Donetsk, Ukraine;(2) Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw, Poland |
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Abstract: | The diamagnetic response of a laser-deposited YBCO film was studied in weak exciting magnetic fields H ac =H 0sinωt (H 0=2–500 mOe, ω/2π=1–30 kHz). An analysis of the experimentally measured diamagnetic response showed evidence of a ring character of the electric field flowing in the sample at small H 0 values. The plots of T m (the temperature of maximum dissipative losses χ″1) versus H 0 measured at various frequencies showed the existence of a certain critical field strength H*(ω) at which the (1?T m /T c ) versus H 0 2/3 plots exhibit a break. A logarithmic dependence of T m on the frequency ω of the exciting field H ac is reliably valid only in the region of (ω/2π)>5 kHz. Verification of the scaling relationship showed that this relationship is valid (to within the experimental accuracy) for the frequencies ω above 5 kHz and the field amplitudes H 0>H*(ω). However, the exponent n in the scaling relationship under consideration is not correlated with the exponent n in the power relationship describing the current-voltage characteristic. |
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