V. N. Fenchenko, Y. S. Yerin
Within the framework of non-stationary Ginzburg-Landau equations generalized
on a case of two order parameters, we investigated dynamic characteristics of
two-band superconducting MgB2 filaments in a voltage-driven regime. We
calculated current-voltage characteristics of superconducting MgB2 filaments
with different lengths and compared with single-band superconductor of
corresponding sizes. Despite the presence of two interacting bands for small
values of a ratio of effective Cooper pairs weights, phenomenological constants
of diffusion and large lengths of channels the well-known S-form of
current-voltage characteristic for the single-band superconductor with
fluctuations of the current density in a certain interval of the voltage also
takes place in the case of two-band superconductor. Analysis of spectra of the
current density and the time-evolution of order parameters for long channels
points out that such unusual forms of current-voltage characteristics are
caused by the occurrence either chaotic oscillations of order parameters
modules or the interference of some their oscillation modes. The further
increase of the ratio of effective weights of Cooper pairs and phenomenological
constants of diffusion smoothes these oscillations and transforms the system in
an ordered state, where the S-form of current-voltage characteristics becomes
more flattened. The latter can be the feature of two-band superconducting long
channels.
View original:
http://arxiv.org/abs/1201.5481
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