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 (C-v) 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 (F-c) it induces special structures in the density of states near the Fermi energy and thus the giant specific heat. At F(c)s, C-v 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 F(c)s, the extra longitudinal magnetic flux could cause a re-enhancement in C-v for ZCNTs, whereas C-v is always diminished for ACNTs. (C) 2014 Elsevier B.V. All rights reserved.