First-Principles Electronic-Structure Study of Graphene Decorated with 4d-Transition Atoms

Adsorption configurations, electronic structures and net spins of graphene adsorbing 4d transition atoms are calculated by first-principles calculations to explore the magnetic modification of decorating metal atoms on graphene. Y, Zr and Nb atoms can be adsorbed on graphene sheet via ionic bonds with an evident charge transfer, while Mo, Tc, Ru and Rh atoms form covalent-like bonding with graphene carbon atoms due to orbital hybridization, as indicated by Mulliken atomic charges and electron density differences. The 4d-transition atoms can be adsorbed on a carbon-ring center and atomic-bridge with a high binding energy as the typical chemisorption, which leads to specific modifications in electronic-band character and magnetic properties by introducing electron-states near Fermi-level. By adsorbing 4d-transition atoms, the electronic structure of graphene will alter from a semi-metal to a metal character, and engender net spin magnetism from the spin-polarization in 5s and 4d orbitals of adsorption atoms. This paper provides a significant theoretical basis for further experimental explorations of the atom-decorated graphene in nanoelectronics.

Transition from Itinerant Electron Magnetism to Localized Spin Magnetism in Ni3Al1-YMny Alloys

Magnetic properties of Ni3Al1-yMny alloys at y≤0.6 were investigated at T≤400 K in magnetic fields H≤4 MA/m. The concentration y dependencies of the spontaneous magnetic moment s, the effective magnetic moment eff, the Curie temperature ТС, the Weiss constant , and the temperature independent part of the magnetic susceptibility 0 were determined. The behavior of the Rhodes-Wohlfarth parameter р(y) in the transition region from the itinerant electron magnetism to the spin localized one is related to the increase in the spontaneous magnetic moment of Ni atoms inversely proportional to the average distance between Mn atoms with the highly localized magnetic moments.