Electron spin relaxation via flexural phonon modes in semiconducting carbon nanotubes

This work considers the g-tensor anisotropy induced by the flexural thermal vibrations in one-dimensional structures and its role in electron spin relaxation. In particular, the mechanism of spin-lattice relaxation via flexural modes is studied theoretically for localized and delocalized electronic states in semiconducting carbon nanotubes in the presence of magnetic field. The calculation of one-phonon spin-flip process predicts distinctive dependencies of the relaxation rate on temperature, magnetic field and nanotube diameter. Comparison with the spin relaxation caused by the hyperfine interaction clearly suggests the relative efficiency of the proposed mechanism at sufficiently high temperatures. Specifically, the longitudinal spin relaxation time in the semiconducting carbon nanotubes is estimated to be as short as 30 microseconds at room temperature.