Thermoelectric effects in electron chiral tunneling in metallic carbon nanotubes

Thermoelectric effects in a metallic single-wall carbon nanotube in the presence of long-range electrostatic and pseudomagnetic potentials (produced by strain) are considered. It is shown that for strong scattering potentials (chiral tunneling) a pronounced energy ”gap” appears in the energy dependence of electron transmission coefficient. This results in strong violation of Wiedemann-Franz law and in a peak-like behavior of thermopower as a function of chemical potential. The electronic figure-of-merit (ZT) is calculated and shown to be sensitive at low temperatures to nanotube chirality. By tuning chemical potential, ZT can reach high values (ZT≃5) that makes specially engineered nanotube-based thermocouple to be a promising nano-device with a high thermoelectric performance.