First principles study of magnetization and magnetic anisotropy energy of small Co-Pt clusters

Abstract

The structural and magnetic properties of Co-Pt clusters up to five atoms with all possible combinations have been studied systematically. The global minimum energy structure of a cluster is obtained by optimizing its different possible geometries by using density functional theory (DFT) approximation. The electronic structure of the clusters were analyzed and found that the hybridization of 3d orbital of Co with the 5d orbital of Pt has enhancement effect on magnetization. The magnetic anisotropy energy of these small clusters is calculated from the free energy difference in two different noncolinear direction of spin alignment. It is found that the cluster with approximately equal number of Co and Pt atoms have larger anisotropy than the clusters with unequal number of Co and Pt of the same size. This can be explained by the combined effect of spin moment, orbital moment and the spin orbit coupling constant of the two materials.

Keywords

• CoPt
• DFT
• Magnetism
• Structure
• Anisotropy
• SOC