Flicker Noise and Telegraph Noise in High-Temperature Superconductors

The mechanism capable to explain the peculiarities of both the telegraph noise and flicker noise in high-temperature superconductors (HTS)—in particular, their common behavior—is proposed. It bases on the impurity mechanism of high-temperature superconductivity and the suggestion that an origin of the flicker noise in most cases is a process that can be described by the equation of diffusion type, with a medium discreteness taken into account. In the transition region, the flicker noise and telegraph noise are explained by fluctuations of the concentration (xef) of the two-level systems each having a localized electron pair. These fluctuations disappear according to the diffusion equation. The telegraph noise is considered as a result of opening and closing superconducting and nonsuperconducting channels due to the xef fluctuations. In the normal state, the flicker noise is explained by concentration fluctuations of different impurities that change the charge carrier mobility.