Reversible transitions in high-Tc cuprates based point contacts

The influence of electric fields and currents has been investigated in the high-Tc superconductors YBaCuO and BiSrCaCuO using a point-contact geometry with Ag as the counter-electrode, which reveal switching transitions between states of a different resistance. The origin of this effect in point contacts is associated with electromigration of the oxygen, driven by the electric field as well as by the current-induced ''electron wind''. The switching effect preserves its basic features at elevated temperatures up to room temperature and in high magnetic fields up to 10 T. (orig.)