Formation of localized magnetic states in graphene in hollow-site adsorbed adatoms

TL;DR

This paper theoretically investigates how transition metal adatoms adsorbed on graphene, especially at hollow sites, can induce localized magnetic states, with implications for spintronic applications.

Contribution

It introduces a tight binding model with Hubbard interactions to analyze localized magnetic states in graphene with adatoms, highlighting differences between adsorption sites.

Findings

Hollow-site adsorption leads to magnetization at lower Hubbard parameters.

Localized magnetic states depend on Fermi energy and adsorption site.

Anomalous broadening enhances magnetic stability.

Abstract

By applying tight binding model of adatoms in graphene, we study theoretically the localized aspects of the interaction between transition metal atoms and graphene. Considering the electron-electron interaction by adding a Hubbard term in the mean-field approximation, we find the spin-polarized localized and total density of states. We obtain the coupled system of equations for the occupation number for each spin in the impurity and we study the fixed points of the solutions. By comparing the top site and hollow site adsorption, we show that the anomalous broadening of the latter allows to obtain magnetization for small values of the Hubbard parameter. Finally, we model the magnetic boundaries in order to obtain the range of Fermi energies at which magnetization starts.