Spin Excitations of Individual Transition Metal Atoms on Cu2N/Cu(100)

ALEJANDRO FERRON; JOSE LUIS LADO; JOAQUÍN FERNANDEZ-ROSSIER

Miraflores de la Sierra, Madrid

Workshop; Summer School Nicolás Cabrera; 2015

INC & Universidad Autonoma de Madrid

We study the nature of spin excitations of individual transition metal atoms (Ti, V, Cr, Mn, Fe, Co and Ni) deposited on a Cu 2 N/Cu(100) surface using both spin-polarized density functional theory (DFT) and exact diagonalization of an Anderson model derived from DFT. We use DFT to compare the structural, electronic and magnetic properties of difffferent transition metal adatoms on the surface. We fifind that the average occupation of the transition metal d shell, main contributor to the magnetic moment, is not quantized, in contrast with the quantized spin in the model Hamiltonians that successfully describe spin excitations in this system. In order to reconcile these two pictures, we build a multi-orbital Anderson Hamiltonian for the d shell of the transition metal hybridized with the p orbitals of the adjacent Nitrogen atoms, by means of maximally localized Wannier function representation of the DFT Hamiltonian. The exact solutions of this model have quantized total spin, without quantized charge at the d shell. We propose that the quantized spin of the models actually belongs to many-body states with two difffferent charge confifigurations in the d shell, hybridized with the p orbital of the adjacent Nitrogen atoms. This scenario implies that the measured spin excitations are not fully localized at the transition metal.