Observation of a sharp lambda peak in the third harmonic voltage response of high-T $ \mathsf {_c}$ superconductor thin films

Abstract

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 7 - δ thin film and in two La2-xSrxCuO4 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.