Shape-dependent magnetic moment and formation energy of Fe heterostructures on Cu(111): An ab initio study

Shape-dependent magnetic moment and island formation energy of Fe adatoms on a Cu(111) surface were systematically investigated using the density functional theory based first-principles calculations. The calculated formation energy of a Fe nanoisland was linearly proportional to the number of Fe-Fe bondings within the island, regardless of the number of Fe atoms or the shape. The magnetic moments of Fe nanoisland atoms were determined by two key factors, the numbers of Fe-Fe bondings and the angles between the Fe-Fe bondings. The magnetic moment of the Fe atom that had the highest number of Fe-Fe bondings was the minimum in all the island models. Through the analysis of the decomposed Fe 3d-electron density of states, we found that the shape-dependency of Fe heterostructures magnetism on Cu(111) results from the preference of Fe atoms to fill certain 3d-electron orbitals according to the Fe-Fe bonding angles.