Fano effect on dynamical conductivity for perpendicular polarization in double-wall carbon nanotubes

The dynamical conductivity of double-wall carbon nanotubes for perpendicularly polarized light to the tube axis is studied by taking into account screening effects, exciton effects and depolarization effects within an effective-mass theory. The exciton peak of the semiconducting inner tube has an asymmetric line shape due to the coupling with a continuum state of the outer tube, indicating the Fano effect. The Fano coupling strength can be tuned by varying the inter-wall distance.