The Edge Current on Zigzag Graphene Nanoribbons

Abstract

We have investigated the electron transport properties of zigzag graphene nanoribbons (GNRs) connected to one-dimensional leads on the edge. Transport properties are calculated using the nonequilibrium Green's function method with a tight-binding scheme. We revealed that an edge current originating in the edge states exists and found that the half width of the resonant peak of the transmission spectrum decays exponentially with increasing width of the GNR.

Spatial current patterns, dephasing and current imaging in graphene nanoribbons

“…N a → ∞, one has a doubly degenerate state at E l = 0 (one localized state at each of the zig-zag edges), and the conductance of the GNR at E = 0 is as expected equal to twice the quantum of conductance. Note that the spatial current pattern in figure 6(b) is qualitatively different from that obtained when wide leads are attached to the armchair edges: in this case, the largest current density occurs in the center of the GNR [1,3,9] and not along the zig-zag edges. On the other hand, when a voltage bias is applied between the zig-zag edges (with chemical potential µ L for leads 1 and 3, and µ R for leads 2 and 4), the current is strongly suppressed (see figure 6(c)), and scales as ∼ E 2 l .…”

“…in close proximity to E = 0, that are delocalized along the zig-zag edge, and localized along the direction of the armchair edge [35]. The form of charge transport through these localized states in the widelead limit has recently attracted some attention [1,3,9], in particular in view of its possible application for DNA sequencing [23]. In figure 6(a), we present the LDOS for a (15 × 7) GNR at E = E l = 4.6 × 10 −13 t, that clearly demonstrates the localized nature of these low energy states.…”

“…Understanding charge transport in graphene nanoribbons (GNRs) has attracted significant interest in recent years [1][2][3][4][5][6][7][8][9][10][11][12], in particular due to their potential application as integrated circuits [13] and field-effect transistors [14][15][16], as bio-sensing devices [17][18][19] and for deoxyribonucleic acid (DNA) sequencing [20][21][22][23]. These unprecedented opportunities have been made possible by experimental advances in creating sub-10 nm wide GNRs [24], in engineering GNRs with specific electronic structures [25], in fabricating high purity samples [26] and in designing artificial molecular graphene [27].…”

Spatial Current Patterns, Dephasing and Current Imaging in Graphene Nanoribbons

“…GNRs possess two low energy states near the middle of the band at ±E l , i.e., in close proximity to E = 0, that are delocalized along the zig-zag edge, and localized along the direction of the armchair edge [35]. The form of charge transport through these localized states in the wide-lead limit has recently attracted some attention [1,3,9], in particular in view of its possible application for DNA sequencing [23]. In figure 6(a), we present the local density of states for a (15 × 7) GNR at E = E l = 4.6 × 10 −13 t, that clearly demonstrates the localized nature of these low energy states.…”

“…Understanding charge transport in graphene nanoribbons (GNRs) has attracted significant interest in recent years [1,2,3,4,5,6,7,8,9,10,11,12], in particular due to their potential application as integrated circuits [13] and field-effect transistors [14,15,16], as bio-sensing devices [17,18,19], and for DNA sequencing [20,21,22,23]. These unprecedented opportunities have been made possible by experimental advances in creating sub-10nm wide GNRs [24], in engineering GNRs with specific electronic structures [25], in fabricating high purity samples [26], and in designing artificial molecular graphene [27].…”