Thermodynamics of two-dimensional cellular domain structures

Experimental and theoretical studies concerning the effects of increasing the temperature or the bias field upon the cellular domain lattices (CDLs) formed in thin ferrite-garnet films, has been performed. It is shown that, if the CDL was formed at room temperature, then, on heating the film, spontaneous transitions occur from the initial CDL to a lattice with a larger domain period and size. A thermodynamic approach based upon the concepts of the domain chemical potential and the domain lattice pressure is developed to describe both the spontaneous and the field-induced transitions. The transitions are discontinuous when the lattice pressure becomes negative. The dependences of the transition temperature and the transition field on the magnetic film parameters and the domain density of the initial CDL are calculated and the form of the CDL phase diagram is found