Electric manipulation of electron spin relaxation induced by confined phonons in nanowire-based double quantum dots

We investigate theoretically the electron spin relaxation in single-electron nanowire-based semiconductor double quantum dots induced by confined phonons and find that the electron spin relaxation rate can be efficiently manipulated by external electric field in such system. An anti-crossing, due to the coaction of the electric field, the magnetic field and the spin-orbit coupling, exists between the lowest two excited states. Both energies and spins of the electron states can be efficiently tuned by the electric field around the anti-crossing point. Multiple sharp peaks exist in the electric-field dependence of the spin relaxation rate induced by the confined phonons, which can be ascribed to the large density of states of the confined phonons at the van Hove singularities. This feature suggests that the nanowire-based double quantum dots can be used as electric tunable on-and-off spin switches, which are more sensitive and flexible than the ones based on quantum-well based double quantum dots. The temperature dependence of the spin relaxation rate at the anti-crossing point is calculated and a smooth peak, indicating the importance of the contribution of the off-diagonal elements of the density matrix to the spin relaxation, is observed. (C) 2011 American Institute of Physics. [doi:10.1063/1.3592340]