We report results of numerical simulations of non isothermal dendritic flux
penetration in type-II superconductors. We propose a generic mechanism of
dynamic branching of a propagating hotspot of a flux flow/normal state
triggered by a local heat pulse. The branching occurs when the flux hotspot
reflects from inhomogeneities or the boundary on which magnetization currents
either vanish, or change direction. Then the hotspot undergoes a cascade of
successive splittings, giving rise to a dissipative dendritic-type flux
structure. This dynamic state eventually cools down, turning into a frozen
multi-filamentary pattern of magnetization currents.Comment: 4 pages, 4 figures, accepted to Phys. Rev. Let
