Influence of substrate effects on the properties of multiferroic thin films

The influence of substrate effects on the ferroelectric and magnetic properties in multiferroic thin films is studied based on the Heisenberg and transverse Ising model. Green's function technique allows the calculation of static and dynamic properties in the dependence on temperature, film thickness and different substrates. It is demonstrated that the polarization, the magnetization, the critical temperatures and the spin-wave energies are very sensitive to the exchange interaction constants between the surface and the substrate and could be increased or decreased by using different kinds of substrates. The dependence on the film thickness is also discussed. The results are in qualitative accordance with the experimental data.