| Popis: |
Spin configurations of an Ising model with competing interactions are calculated numerically within a mean field theory. The phase diagram has a large number of different commensurate phases. Near the transition from a paramagnetic to a modulated phase, the width of the higher-order commensurate phases becomes very narrow. With decreasing temperature, the lower-order commensurate phases becomes very narrow. With decreasing temperature, the lower-order commensurate phases occupy the whole phase diagram. Even at zero temperature, a finite number of commensurate phases are stable unlike in the ANNNI model because of effectively long-range interactions. The phase boundary of the commensurate phase is analysed analytically by a revised phase soliton theory and it is compared with the numerical results. |
