3 Temperature dependence of macroscopic anisotropy in thin films with Néel surface anisotropy

Due to the flexibility of the constrained Monte Carlo method it is a perfect tool to investigate and understand the temperature dependence of the Néel surface anisotropy (NSA).

The surface anisotropy is normally found to be much stronger than bulk anisotropy, so that a value of $K_{s}=10\cdot K_{c}$ was chosen. In the simulation of thin films we have imposed periodic boundary conditions in $2D$ with the aim to avoid the edge effects. When studying thin films with surface anisotropy, a number of basic combinations of anisotropies are possible. Principally, in the case of bulk uniaxial anisotropy, the surface and bulk anisotropies can have aligned or opposite directions of easy axes, depending on the sign of the constants. Alternatively, a material could possess a cubic bulk anisotropy and uniaxial surface anisotropy. In the following we present calculations of temperature dependent effects in these thin film systems with surface anisotropy.