Generalized stacking fault in FePt nanoparticles and effects of extended defects on magnetocrystalline anisotropy energy

We applied the concept of the generalized stacking faults energy to calculate the effect of the slip on the magnetocrystalline anisotropy of FePt nanostructures. We calculated γ-surface energy of L10 FePt by shifting two crystallites against each other using slab approach for slips in (1 1 0) and (0 0 1) planes in regular lattice and in antiphase boundary (APB) along the path connecting the high symmetry points of γ-surface. We estimated the energy density of unstable point of γ-surface of regular slip and APB slip to be about 1.05 J/m2 and 0.58 J/m2, respectively, while the brittle cleavage energy densities are of 1.74 J/m2 and 1.1 J/m2, respectively. Local magnetic moments do not change significantly in the presence of the slip. We find that the slip in (1 1 0) and (0 0 1) planes affect strongly the magnetocrystalline anisotropy energy (MAE) increasing it for the slip in regular L10 FePt, while decreasing it in case of slip in APB plane. We found MAE change associated with the slip at the unstable point of γ-surface is substantial with the energy densities of 0.663 J/m2 and 1.74 J/m2 for (1 1 0) and (0 0 1) planes, respectively. Thus, extended defects may affect the magnetization reversal of FePt nanoparticles.