Influence of growth conditions and weak fields on the electrical properties of the vortex and superconducting states of Bi2Sr2CaCu2Ox thick tapes

The current-voltage characteristics (I-V) for various samples of different growth conditions and applied fields were also investigated. The study revealed a current dependence on the applied voltage was found to fit a power law of the form: I ∼ Vα, where α is an exponent whose values are strongly dependent on growth conditions. At constant voltages, the current was found to decrease exponentially with the applied magnetic field according to I(B) ∼ exp(−cB/B∗), where c is a constant depending on growth conditions and B∗ is a characteristic field of the sample. This exponential decay of the current is attributed to strong flux pinning centers. The dependence of the current on field and voltage could be written as I ∼ Vαexp(−cB/B∗). Furthermore, the heat treatment conditions and annealing atmosphere had strong influence on the I-V characteristic of the sample.