Structure, bonding and magnetism in cobalt clusters

TL;DR

This study uses density functional theory to explore the structure, bonding, and magnetic properties of cobalt clusters with sizes from 2 to 20 atoms, revealing unique growth patterns and magnetic behaviors.

Contribution

It provides new insights into the structural and magnetic characteristics of cobalt clusters, highlighting the influence of coordination and hybridization on magnetism.

Findings

Hexagonal growth pattern in intermediate-sized clusters

Cobalt atoms exhibit ferromagnetic order with enhanced magnetic moments

Magnetic moments are influenced more by coordination number than bond length

Abstract

The structural, electronic and magnetic properties of Co$_n$ clusters ($n=2-$20) have been investigated using density functional theory within the pseudopotential plane wave method. An unusual hexagonal growth pattern has been observed in the intermediate size range, $n=15-$20. The cobalt atoms are ferromagnetically ordered and the calculated magnetic moments are found to be higher than that of corresponding hcp bulk value, which are in good agreement with the recent Stern-Gerlach experiments. The average coordination number is found to dominate over the average bond length to determine the effective hybridization and consequently the cluster magnetic moment.