Band Structure of Single-Walled Carbon Nanotubes (SWCNTs) under the influence of Elastic Deformation and Magnetic Field


We investigate the electronic band structure of SWCNTs exposed to the elastic mechanical deformation and external magnetic field along axis of the tubes. Our theoretical calculations were accomplished by using the dispersion relation of π-electrons in the tight binding approximation for armchair, zig-zag and chiral SWCNTs under the influence of the helical deformation and uniaxial tension in the case of the presence or absence of a magnetic field. The exponential expression has been used for the matrix element of the Hamiltonian operator, which is exponentially proportional to the distance between the carbon atoms in the SWCNT. The energy gap for armchair (10,10) SWCNT increases under the helical deformation with the absence of the magnetic field, consequently, the SWCNT will turn from conducting to semiconducting. In contrast, the energy gap for armchair (10,10) SWCNT is unchangeable under the influence of the uniaxial tension. Moreover, we have noticed the growth of the energy gap for armchair (10,10) SWCNT when the tube is exposed to an external magnetic field. We observed a different behavior for zig-zag (9,0) SWCNT, where the energy gap increases slightly when applying helical deformation and rapidly under the uniaxial tension without a magnetic field. Through our study of the band structure for chiral (10,9) SWCNT, we found that it is not significantly affected when applying the two patterns of mechanical deformation. The presence of the magnetic field in chiral (10,9) SWCNT causes a decrease in the energy gap and thus increases the electrical conductivity of this tube. The variations in the energy gap values can be practically used in the nanosystems based on carbon nanotubes such as CNT field-effect transistors, nanosensors and other practical applications in the field of nanoelectronics.