Surface and interface magnetic effects in CoNRhM clusters

The spin moments, orbital moments, and magnetic anisotropy energy (MAE) of CoNRhM clusters having N ⩽ 321 atoms are investigated in the framework of a self-consistent electronic model Hamiltonian. Alloying Co clusters with Rh results in a significant enhancement of the magnetization per Co atom. This is mainly due to the spin moments 〈Siz〉 induced at the Rh atoms, which amount to about 20% of the moment per Co atom (〈Siz〉 = (0.2–0.3)μB), and to an enhancement of the orbital moments of the Co atoms at the Co–Rh interfaces. The calculated MAEs reveal remarkable changes in the easy axis as a function of concentration. The magnetic properties are analyzed from a local perspective. The role of the chemical arrangement of Co and Rh atoms within the cluster is discussed.