Magnetoresistance of Mn-decorated topological line defects in graphene

Abstract

We study the spin polarized transport through Mn-decorated 8-5-5-8 topological line defects in graphene using the nonequilibrium Green's function formalism. Strong preferential bonding overcomes the high mobility of transition metal atoms on graphene and results in stable structures. Despite a large distance between the magnetic centers, we find a high magnetoresistance and attribute this unexpected property to very strong induced π magnetism, in particular for full coverage of all octagonal hollow sites by Mn atoms. In contrast to the magnetoresistance of graphene nanoribbon edges, the proposed system is well controlled and therefore suitable for applications.

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 .…”

“…Compared with Fe[P]/GB (5)(6)(7)(8), in Fe[P]/GB(5-7) there is an increase of the Fe[P]-Fe[P] distance between the pentagonal sites, 6.63Å. In GB (5)(6)(7)(8) 18,19 . However, along the LX direction of the spin-down channels, we find metallic states composed by Mn-3d states hybridized with the graphene-π orbitals, giving rise to a Dirac-type cone at about E F + 0.3 eV.…”

“…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.…”

“…In a recent experimental work 17 , the authors verified that the performance of hydrogen gas sensors was improved, upon the formation of linear structure of Pt adatoms along the GB sites. Further theoretical studies indicate that NLs of Fe and Mn adatoms lying along the GBs, composed by a pair of pentagons and an octagon 10 , give rise to half-metallic nature for the electronic transport along the Fe or Mn decorated GB sites 18,19 . Indeed, somewhat similar spin-polarized current, dictated by the presence of foreign atoms, has been predicted along the edge sites of graphene nanoribbons 20,21 .…”