Phase transitions with spontaneous modulation-the dipolar Ising ferromagnet

A uniaxial ferromagnet of finite thickness spontaneously breaks into parallel "striped" domains as a result of demagnetizing forces. In a sufficiently large applied magnetic field a transition takes place to a hexagonal or "bubble" phase. We study the phase diagram of this system with the use of a Ginzburg-Landau approach and we investigate the effects of dislocations on the two-dimensional order of the modulated phases.