Specificity of the nonlinear response of Y-Ba-Cu-O ceramic superconductors near the transition point

The nonlinear properties of ceramic YBaCuO samples near the superconductivity transition point are investigated experimentally. The temperature and field dependences of the detecting signal are obtained. It is shown, in particular, that in a strong field the magnitude of the nonlinear response is proportional to H-q, the exponent q being dependent on the temperature. Expressions for the detection signal that describe qualitatively the experimental results are derived on the basis of the self-consistent equations of dynamics of a Josephson medium