Origin of room-temperature single-channel ballistic transport in zigzag graphene nanoribbons

Abstract

Very recently, it was demonstrated explicitly that a zigzag graphene nanoribbon (GNR) exhibits a conductance of G0/2 (G0 = 2e2/h is the quantum of conductance) even at room-temperature along distances as large as 16 micron [Baringhaus, et al. Nature 506, 349 (2014)]. Such a result is puzzling as none of previous theories seem to match the experimental observations. Here, we propose a model to explain the robust single-channel ballistic transport properties in zigzag GNR. The sp3 distortion of carbon atoms at the GNR edges induces a large spin-orbit coupling of edge atoms, which enhances spin-flip scattering of edge states of the zigzag GNR. With sufficient spin-flip scattering, the wave-function of the edge states becomes a superposition of the spin-up and spin-down components. This removes the spin degree of freedom and results in the robust conductance of G0/2 in the zigzag GNR.