Field-enhanced electronic specific heat of carbon nanotubes

The tight-binding model including curvature effects is used to study the effect of transverse electric field on the low-temperature electronic specific heat (Cv) for armchair and zigzag carbon nanotubes (ACNTs and ZCNTs). Electric field could effectively modulate energy dispersions of CNTs and cause a shift of electronic states toward the Fermi energy. As field strength reaches to a critical value (Fc), it induces special structures in the density of states near the Fermi energy and thus the giant specific heat. At Fcs, Cv has a value comparable to that of the phonon specific heat and reveals strongly non-linear dependence on temperature. The critical field strength and giant specific heat are closely related to nanotube's geometry. Moreover, under Fcs, the extra longitudinal magnetic flux could cause a re-enhancement in Cv for ZCNTs, whereas Cv is always diminished for ACNTs.