Ab initio magnetocrystalline anisotropy at nanoscale: The case of FePt

The effect of the transition from bulk to nanoscale on the magnetocrystalline anisotropy (MCA) is studied from first principles for L10-ordered FePt nanoslabs and nanocrystals. It is shown that the nano size of slabs does not kill bulk MCA but may even slightly increase it. The effect of lattice parameter change on MCA is much stronger than that of slab thickness. The design of the shape of a nanocrystal may also be used to increase the MCA.