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

TL;DR

This paper theoretically explores how electric fields can control electron spin relaxation in nanowire-based double quantum dots, revealing sharp peaks in relaxation rates linked to phonon density of states, enabling tunable spin switches.

Contribution

It demonstrates electric field manipulation of spin relaxation rates via confined phonons, highlighting the potential for highly sensitive, electrically tunable spin switches in nanowire quantum dot systems.

Findings

Electric fields can efficiently tune spin relaxation rates.

Sharp peaks in relaxation rates correspond to phonon van Hove singularities.

Nanowire quantum dots can serve as sensitive, tunable spin switches.

Abstract

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 fields 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 are 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.