The main results of the study of the energy landscape in magnetic nanoparticles with different lattices, shapes and the Néel surface anisotropy model are summarized as follows:
- Our numerical calculations have shown that the magnetic behavior of the nanoparticles with Néel surface anisotropy is consistent with the effective one spin particle (EOSP) model with uniaxial and cubic anisotropies. The strength and sign of these additional effective anisotropy constants are dependent on many parameters, including the shape and elongation of the particle, and the underlying crystal structure which produces different spin surface arrangement.
- We have compared the analytical and numerical results for the energy landscapes for many-spin particles cut from sc lattice obtaining a very good agreement.
- We have observed that the cubic anisotropy contribution due to the surface of magnetic nanoparticles has an opposite sign in the case of sc and fcc underlying lattice structures.
- We have studied numerically the effective energy of Co multi-spin nanoparticle with an octahedral shape, fcc lattice structure and cubic core anisotropy as a function of the surface anisotropy magnitude. The results indicate that the surface anisotropy introduces an additional first and second order cubic anisotropy. For elongated particles they also induce an additional uniaxial anisotropy.