Branching instability in the flux creep regime of type-II   superconductors
  We study theoretically the space-time evolution of the thermal and electromagnetic perturbation in a superconductor with a nonlinear current-voltage characteristics in the flux creep regime. On the basis of a linear analysis of a set of differential equations describing small perturbations of temperature and electromagnetic field, it is found that under some conditions a branching instability may occur in a superconductor sample. 
N. A. Taylanov
cond-mat.supr-con