Quantum interference effect in the nonlinear conductance of metallic single-wall nanotubes

The nonlinear quantum conductance of a metallic single-wall nanotube induced by a few single impurities, is studied theoretically. It is shown that the conductance is an oscillatory function of applied voltage and oscillation pattern depends on the diameter of nanotube and spatial distribution of impurities on it.

Figure 1

The model of the SWNT in the form of a long cylindrical surface of the radius $R$, which smoothly connects two massive metallic reservoirs. The impurities on the surface of the cylinder are shown schematically.

Figure 2

The first order correction to the conductance resulted by point impurities, $G_1$ as a function of voltage for a model NT with two impurities, one impurity located at $(R,0,20{\lambda }_F)$ but position of the second impurity $(R,\pi ∕3,z_2)$, is different in different curves. In Figs. 2, 3, 4, 5, values in the vertical axis are scaled by ${10}^3{g}^2∕16{\epsilon }_F^2{\lambda }_F^4=1$.

Figure 3

$G_1$ as a function of voltage for a model NT with two impurities, one impurity located at $(R,0,20{\lambda }_F)$ but position of the second impurity $(R,{\theta }_2,70{\lambda }_F)$, is different in different curves.

Figure 4

$G_1$ as a function of voltage for a model NT with two fixed impurities. Each curve corresponds to a tube with specified radius.

Figure 5

$G_1$ as a function of voltage. Different curves correspond to NTs with different number of impurities, $n$.