Chiral tunneling in metallic carbon nanotubes

The concept of chiral tunneling in metallic single-wall carbon nanotubes, originating from the interplay of local electrostatic and pseudomagnetic potentials, is considered and applied to an evaluation of the Josephson current in a nanotube-based superconductor–normal metal–superconductor (SNS) junction and the persistent current in a circular nanotube. In the former case, an oscillatory dependence of the critical supercurrent on the potential strength and the nanotube chiral angle is predicted. In the latter case, the existence of a spontaneous persistent current in an isolated ringlike nanotube is discussed.

Figure 1

Transmission coefficient as a function of chiral angle at different values of potential strength (solid curve for $U_0=11$ and dashed curve for $U_0=6.5$) and as a function of $V_d/V_o$ (inset) at $U_0=8$ for different chiral angles (solid curve for $\mathrm{\theta ̃}=0.52$ and dashed curve for $\mathrm{\theta ̃}=0.2$).

Figure 2

The Josephson critical current (in units of $e{\Delta }_0/\hslash$) in a short junction as a function of the potential strength $U_0$ for chiral angles $\mathrm{\theta ̃}=0.52$ (solid curve) and $\mathrm{\theta ̃}=0.2$ (dashed curve).

Figure 3

Spontaneous persistent current (in units of $I_0=e{v}_F/L$) as a function of chiral angle $\mathrm{\theta ̃}$ for the potential strength $U_0=15$.