Josephson mechanism in random telegraph voltage noise in high-Tc superconductors

Random telegraph voltage noise signals characterized by strongly nonlinear and nonmonotonic dependence of the telegraph amplitude on current flow has been observed in good quality epitaxial BiSrCaCuO thin film strips biased with d.c. current flow and immersed in an external magnetic field. The shape of the amplitude dependence on current flow closely resembled that observed previously in granular films, where intergranular Josephson junctions were involved in noise generation. The dependence of noise amplitude on bias current and magnetic field in epitaxial films is discussed in the context of the possible Josephson flux-to-voltage conversion mechanism.