Atomic structure, alloying behavior, and magnetism in small Fe-Pt clusters

We report results of the atomic structure, alloying behavior, and magnetism in FemPtn clusters using projector augmented wave (PAW) pseudo-potential method and spin-polarized generalized gradient approximation (GGA) for the exchange-correlation energy. These results are compared with those obtained by using HCTH exchange-correlation functional and LANL2DZ basis set in the Gaussian program and the overall trends are found to be similar. As in bulk FePt alloys, clusters with equal composition of Fe and Pt have the largest binding energy and the largest heat of nano-alloy formation for a given number of atoms in the cluster. We discuss the hybridization between the electronic states of Pt and Fe atoms as well as the variation in the magnetic moments on Fe and Pt atoms. Our results provide insight into the understanding of the nano-alloy behavior of FePt and we hope that this would help to design Fe based nano-alloys and their assemblies with high magnetic moments for strong magnets without rare earths as well as Pt alloy catalysts.