EVOLUTION OF DISORDER IN 2-DIMENSIONAL STRIPE PATTERNS - SMECTIC INSTABILITIES AND DISCLINATION UNBINDING

A combination of video polarization microscopy and extensive digital line pattern analysis has been invoked to examine in quantitative detail the transformation of a lamellar into a "labyrinthine" magnetic-stripe domain pattern. The evolution of disorder is found to be mediated by a sequence of transverse, "smectic" instabilities culminating in the generation of disclination dipoles. Their subsequent continuous "unbinding" facilitates the formation of a globally isotropic nonequilibrium pattern adopting the topology of a binary tree and displaying a well-defined morphology with a motif in the form of oblong, polygonal clusters of linear-stripe segments.