▎ 摘　　要

Very recently, it was demonstrated explicitly that a zigzag graphene nanoribbon (GNR) exhibits a conductance of G(0)/2 (G(0) = 2e(2)/h is the quantum of conductance) even along distances as large as 16 mu m at room-temperature (Baringhaus et al. 2014). Such a result is puzzling as none of previous theories seem to match the experimental observations. Here, a model was proposed to explain the robust single-channel ballistic transport properties in zigzag GNR. The sp(3) distortion of carbon atoms at the GNR edges induces a large spin-orbit coupling on the edge atoms, which enhances spin-flip scattering of the 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. Then the coupling of the two edges becomes important. This removes the edge degree of freedom and results in the robust conductance of G(0)/2 in the zigzag GNR.