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

摘要

Motivated by recent experiments of successfully carving out stable carbonatomic chains from graphene, we investigate a device structure of a carbonchain connecting two zigzag graphene nanoribbons with highly tunablespin-dependent transport properties. Our calculation based on thenon-equilibrium Green's function approach combined with the density functionaltheory shows that the transport behavior is sensitive to the spin configurationof the leads and the bridge position in the gap. A bridge in the middle givesan overall good coupling except for around the Fermi energy where the leadswith anti-parallel spins create a small transport gap while the leads withparallel spins give a finite density of states and induce an even-oddoscillation 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 associatedwith the spin-polarized edge states, presenting sharp pure $\alpha$-spin and$\beta$-spin peaks beside the Fermi energy in the transmission function. Thismakes it possible to realize on-chip interconnects or spintronic devices bytuning the spin state of the leads and the bridge position.