1202.5415 (Yuehua Xu et al.)

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

Yuehua Xu, Bao-Ji Wang, San-Huang Ke

Motivated by recent experiments of successfully carving out stable carbon
atomic chains from graphene [Meyer et al. Nature (London) 454, 319 (2008); Jin
et al. Phys. Rev. Lett. 102, 205501 (2009)] 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 contact position in the gap. A connection 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 connection at the edge shows a transport behavior
associated with the spin-polarized edge states, presenting sharp pure
$\alpha$-spin and $\beta$-spin peaks beside the Fermi energy in the
transmission function. This makes it possible to realize on-chip interconnects
or spintronic devices by simply changing the spin configuration of the leads
and the position of the connection.

View original: http://arxiv.org/abs/1202.5415