4 research outputs found
Higher harmonics of ac voltage response in narrow strips of YBa2Cu3O7 thin films: Evidence for strong thermal fluctuations
We report on measurements of higher harmonics of the ac voltage response in
strips of YBa2Cu3O7 thin films as a function of temperature, frequency and ac
current amplitude. The third (fifth) harmonic of the local voltage is found to
exhibit a negative (positive) peak at the superconducting transition
temperature and their amplitudes are closely related to the slope (derivative)
of the first (Ohmic) harmonic. The peaks practically do not depend on frequency
and no even (second or fourth) harmonics are detected. The observed data can be
interpreted in terms of ac current induced thermal modulation of the sample
temperature added to strong thermally activated fluctuations in the transition
region.Comment: 9 pages, 4 figures (PDF file
Observation of a sharp lambda peak in the third harmonic voltage response of high-T
In this paper, we report on the sharp peak observed in the third
harmonic voltage response generated by a bias sinusoidal current
applied to several strips patterned in a
YBa2Cu3O thin film and in two
LaSrxCuO4 thin films, when the temperature is close
to the normal-superconductor transition. The lambda-shaped
temperature dependence of the third harmonic signal on the current
characteristics is studied. Several physical mechanisms of third
harmonic generation are examined