3 Surface effects in nanomagnets

In ferromagnetic bulk materials, the magnetostatic interaction and bulk magneto-crystalline anisotropy are the principal sources of the anisotropy, but when we are working with nano-scale systems, such as thin films, nanoparticles, wires, etc. strong surface effects are expected. As the particle size decreases, the surface and interface effects are enhanced due to the increase of the surface/volume ratio. The surface effects can yield different magnetic properties of a low-dimensional system with respect to the typical bulk ones. The principal surface effects will be briefly discussed in below:

In practice it is impossible to separate these effects and consequently, all of them are normally embedded in the phenomenological concept of the "surface anisotropy". The detailed theoretical description of real experimental situation is almost impossible due to competition of many effects and large dispersion of individual nanoparticles properties.

Rocio Yanes