Dynamics of the labyrinthine patterns at the diffuse phase boundaries

The phase diagram of a magnetic colloid in a. Hele-Shaw cell is calculated. As a function of the magnetic field strength, of the concentration and of the layer thickness the magnetic colloid can find itself in a stripe phase, the hexagonal phase or in an unmodulated state. Those results allow to int erpret experiments observing the transformation of a labyrinthine pattern i nto a hexagonal structure. This possibility is confirmed directly by the nu merical simulation presented here and showing the transformation of the lab yrinthine pattern into the hexagonal structure.