Highly tunable spin-dependent electron transport through carbon atomic chains connecting two zigzag graphene nanoribbons

Abstract

Motivated by recent experiments of successfully carving out stable carbon atomic chains from graphene, we investigate a device structure of a carbon chain connecting two zigzag graphene nanoribbons with highly tunable spin-dependent transport properties. Our calculation based on the non-equilibrium Green's function approach combined with the density functional theory shows that the transport behavior is sensitive to the spin configuration of the leads and the bridge position in the gap. A bridge in the middle gives an overall good coupling except for around the Fermi energy where the leads with anti-parallel spins create a small transport gap, while the leads with parallel spins give a finite density of states and induce an even-odd oscillation in conductance in terms of the number of atoms in the carbon chain. On the other hand, a bridge at the edge shows a transport behavior associated with the spin-polarized edge states, presenting sharp pure α-spin and β-spin peaks beside the Fermi energy in the transmission function. This makes it possible to realize on-chip interconnects or spintronic devices by tuning the spin state of the leads and the bridge position.

Twist Effect on the Electronic and Transport Properties of 1D Helical Carbyne Chains

“…Similarly, the results are consistent with that of straight (λ ¼ 0 Å) carbon wires, which show sharp resonance peaks and only slight spin polarization in the energy window [À1,1] eV (Figure 6a). [25] However, when λ is 4.5 Å, a significant spin polarization at the Fermi level will appear, which is close to 100%. Note that this behavior is different from Figure 5a, in which the α-spin state electrons provide the main transport channel.…”

“…To further diversify the spintronic function of the on-chip interconnection, we also consider different chain-lead couplings for the six-member unclosed ring-connected junctions as proposed in previous works. [18,25] The devices are shown in Figure S8, Supporting Information. The transmission spectra and transport eigenstates of the C 8 -HCCs with pitches of 0, 4.5, and 6.5 Å connecting ZGNRs leads under P magnetism configuration are shown in Figure 6.…”

“…[18][19][20][21][22][23] Currently, some reports on the transport properties of carbon chain-ZGNR junctions have been presented. [24,25] Moreover, the applications of carbynebased structures have been widely investigated. [26][27][28][29][30][31] The longitudinal straining and lateral bending of sp carbon chains are found to have higher deformation ability and elastic property than quasi-1D CNTs.…”

Progressive structural and electronic properties of nano-structured carbon atomic chains

“…Due to the metallic character and good conductance, ZGNRs are chosen as the electrodes and the transport properties of chain-ZGNR junctions are extensively studied by several research groups. [16][17][18][19][20] However, AGNRs are not choosen as the electrodes because of their semiconducting or semimetallic nature, providing poor conductance. Theoretical results for transport along GNR-CAC-GNR have recently been presented.…”

“…The findings of Lang and Avouris 16 show that odd-numbered chains have lower resistance (higher conductance) than even-numbered chains due to high DOS at their Fermi level. Xu et al 20 have considered different bridge positions for the CAC between ZGNRs and their results indicate that the transport behavior is sensitive to the bridge position and the spin configuration of the leads.…”