Magnetoresistance of Mn-decorated topological line defects in graphene

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 $\pi$ 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.

Figure 1

Structure of (a) graphene, (b) graphene with line defect, and (c) graphene with 50% Mn-decorated line defect. The labeling of the C atoms takes into account the symmetry of the structure.

Figure 2

Band structures of graphene (a) without and (b) with line defect. Both cases show spin degeneracy.

Figure 3

Spin polarized band structures and partial densities of states for (top) 50% and (bottom) 100% Mn coverage.

Figure 4

Modification of the total magnetic moment by strain along the $x$ axis and in the $xz$ plane for 100% Mn coverage.

Figure 5

Transmission coefficient at zero bias for the (a) pristine, (b) 50% Mn-decorated, and (c) the 100% Mn-decorated line defect.

Figure 6

I-V characteristics for the P and AP configurations of the (a) pristine, (b) 50% Mn-decorated, and (c) 100% Mn-decorated line defect. (d) Magnetoresistance for case (c).