A calculation method based on fast Fourier transformation and micromagnetism (FFTM) is presented.It is applied to the numerical calculation of two-dimensional nanomagnetic systems.Numerical calculations show that the results of FFTM method are similar to those of the method in which the dipole-dipole interaction is performed straightforward with truncation.The precision and the speed of calculation are improved.It is shown that the FFTM method provides a fast and efficient way for magnetic systems with long-range dipole-dipole interaction.

Magnetic feature of a two-dimension ferromagnetic/antiferromagnetic random diluted magnetic system is studied by micromagnetism and Monte Carlo method. The step effect of M-H magnetization curve is found in this system, and discussed with the one-dimension Ising model, which covers the energy of system and the spin configuration. It's found that the step effect can be produced in the antiferromagnetic coupling system with small number of spins.

The spin reorientation of magnetic thin film on a simple cubic lattice is simulated by employing Monte Carlo method.The influence of the magnetic anisotropy and the long-range dipolar interaction on the spin configurations of the system is also studied in detail.Meanwhile,the phase diagrams and the distributions of spin configuration,magnetization,specific heat of the systems are obtained.The results show that in a range of parameters,a transition from out-of-plane to in-plane ordering with the increase of the temperature is possible.