Nearly pefect single-channel transport in disordered armchair nanoribbons

Now we turn to the discussion of the electronic transport properties of disordered metallic armchair nanoribbons. Figure 8(a) shows the averaged conductance h g i as a function of the ribbon length L in the presence of LRI for several different Fermi energies E. As we can clearly see, the averaged conductance subjected to LRI in the single-channel transport (E = 0.1,0.2 and 0.3) is nearly equal to one even in the long wire regime. This result is contrary to our expectation that electrons are scattered even by LRI, since wave functions at K ₊ and K − points are mixed in armchair nanoribbons as we have already seen in section 2.2.2. For multi-channel transport (E > 0.4), the conductance shows a conventional decay. The robustness of single-channel transport can be clearly viewed from the Fermi energy dependence of conductance for several different ribbon lengths L as shown in figure 8(b). It should be noted that the energy dependence in the vicinity of E = 0 is quite different from that in zigzag nanoribbons. The conductance decays rapidly due to the finite ribbon width effect in zigzag ribbons [23], while the conductance around E = 0 remains unity in armchair ribbons

(figure 8(b)).

Now let us see the effect of SRIs. Figure 8(c) shows the average conductance h g i as a function of the ribbon length L in the presence of SRI for several different Fermi energies E. In this case, the conductance decays exponentially even for single-channel transport. This result is similar to that previously obtained in zigzag nanoribbons. However, the rate of decay in the low-energy single-channel regime (E = 0.1 and 0.2) is slower than that for the multi-channel transport regime (E > 0.4) in this case. Similar results are obtained in [75], but in which only short-range disorder at the edge of ribbons is considered.