Morphology and local structure in labyrinthine stripe domain phase.

Analysis of globally disordered, nonequilibrium "labyrinthine" stripe-domain patterns in thin ferrimagnetic garnet films has revealed a well-defined local structure containing an oblong polygonal plaquette as the fundamental motif. Two types of labyrinths were found: one having topological defects, the other composed of a single, unbranched, meandering line. These patterns emerge when the labyrinthine state is approached either by heating at constant magnetic field or by demagnetizing from saturation at constant temperature. Size and aspect ratios of the oblong polygonal plaquettes prove to be independent of the choice of these two mutually orthogonal trajectories within the phase diagram, which is surprising in view of the different mechanisms and concomitant topological constraints governing the evolution of disorder. The significance of this unique local structure is discussed in the general context of defectmediated melting of two-dimensional stripe phases.