First-principles study of 3d transition metal atom adsorption onto graphene: the role of the extended line defect

Abstract

A type of extended line defect (ELD) with two pentagons plus an octagon as the basic unit is currently an experimentally available topological defect in the graphene lattice, which brings about some interesting modifications to the electronic properties of graphene. Within the framework of density functional theory (DFT), we perform a systematic calculation to clarify the role of the ELD in 3d-transition metal atom (TMA) adsorption onto the graphene surface. We find that, in contrast to the ordinary lattice position of graphene, the ELD presents a much stronger adsorption for the TMAs(Sc-Cu). Thus, the presence of ELD provides a feasible approach to pattern magnetic impurities onto the graphene surface in a controllable and self-assembled way. In addition, our calculation indicates that as the adatom near the ELD alters from Sc to Cu, the spin moment and the adsorption energy show intricate variations. By means of symmetry analysis, we establish a hybridization picture between the TMA orbitals and the p z orbital of graphene, by which these numerical results are reasonably explained. Finally, by calculating the electronic transport properties based on the DFT and nonequilibrium Green function technique, we find that when the electron tunnels through an ELD with Co or Fe adsorption, the maximum spin-filter efficiency can reach 85% and 97%, respectively, with a bias voltage less than 0.6 V. Therefore, these composite structures of graphene with TMA adsorbed by the ELD can be considered as a prototype of a spin-filter device.

Nanolines of transition metals ruled by grain boundaries in graphene: An ab initio study

“…Our results of adsorption energies and the net magnetic moments are summarized in Table II. The energetic preference for Fe[P]/, and Co[P]/GB (5)(6)(7)(8) are in agreement with the previous theoretical studies 18,19,31 , however, the same does not occur for the Mn adatom. We find an energetic preference for the pentagonal sites, Mn[P]/GB(5-8) 31 , instead of Mn[O]/GB(5-8) 18,19 .…”

“…The energetic preference for Fe[P]/, and Co[P]/GB (5)(6)(7)(8) are in agreement with the previous theoretical studies 18,19,31 , however, the same does not occur for the Mn adatom. We find an energetic preference for the pentagonal sites, Mn[P]/GB(5-8) 31 , instead of Mn[O]/GB(5-8) 18,19 . In order to verify the accuracy of our results, we have performed additional calculations including up Mn-3s as valence orbitals for the Mn pseudopotential, (i) within the PAW approach 25,32 , and (ii) using ultrasoft Vanderbilt pseudopotentials 33 .…”

“…On the other hand, such a spin-anisotropy has been suppressed in AFM Fe[PO]/ and Fe[PP]/GB (5)(6)(7)(8), where we find semiconductor systems (not shown). Indeed, spin-depend electronic current, perpendicular to the GB sites, has been proposed for other TM geometries on Gb(5-8) 31 . In Fig.…”

“…In general, the electronic band structure of GB (5)(6)(7)(8), near E F , has been somewhat preserved for the spin-up channel of Fe[P]/GB(5-8), but not for the spin-down channel. Half-metal behavior has been proposed for Fe/ and Mn/GB(5-8) 18,19,31 . Here we show that the half-metal behavior in Fe[P]/GB(5-8) is ruled by a hybridization between the Fe-4s and the host π orbitals [c1 in Fig.…”

Induced ferromagnetism on late transition metals adsorbed on Antimony Arsenide monolayer from First-Principles

“…Interestingly, defects, adsorption and substitution of either magnetic or nonmagnetic elements have been reported to show magnetic ordering in 2D materials, which opens the way to the design of 2D type magnetic material [11,8,9,12,10]. In this area, transition metal (TM) atoms are often used to modulate electronic and magnetic properties of 2D materials, which can facilitate the use of these materials in spintronic applications [13,14,15]. Tremendous research efforts has focused on the TM adsorption on 2D systems.…”