Remanent magnetization of high-temperature Josephson junction arrays

In this work we study the remanent magnetization exhibited by tridimensional disordered high-Tc Josephson junction arrays excited by an AC magnetic field. The effect, as predicted by numerical simulations and previously verified for a low-Tc array of Nb, occurs in a limited range of temperatures. We also show that the magnetized state can be excited and detected by two alternative experimental routines. In a recent work we have demonstrated that Josephson junction arrays (JJAs) fabricated from granular Nb may exhibit a magnetic remanence, Mr, upon excitation by a magnetic field. As predicted, the magnetized state occurs in a window of temperatures, whose extent depends on the critical current, Jc, of the junctions. Also, there is a threshold value for the magnetic field in order to drive the JJA to the state where flux is retained after suppression of the field. In Ref. 1 we have also shown that the profile of Mr is sensitive to the critical current dispersion, what stresses the prospective use if this effect as a suitable tool for determining the critical current distribution of the array, N(Jc). This contribution presents selected parts of a systematic study of the remanent magnetization displayed by our newly produced high-temperature tridimensional disordered arrays (3D-DJJAs), fabricated from granular YBa2Cu3O7−δ. The experimental results confirm the predictions, revealing that the remanence develops in a limited range of temperature.