Spontaneous and resonant lifting of the spin blockade in nanowire quantum dots

TL;DR

This paper provides a detailed numerical analysis of charge and spin dynamics in nanowire quantum dots, revealing how spin-orbit coupling and phonon interactions can lift the spin blockade, aligning with recent experimental observations.

Contribution

It offers the first comprehensive numerical model explaining the mechanisms behind spin blockade lifting in nanowire quantum dots under oscillating electric fields.

Findings

Spin-orbit coupling enables phonon-mediated relaxation that lifts the spin blockade.

The blockade is suppressed when the initial state is close in energy to the ground state.

A new resonance channel appears after the singlet-triplet ground-state transition at higher magnetic fields.

Abstract

A complete numerical description of the charge and spin dynamics of a two-electron system confined in narrow nanowire quantum dots under oscillating electric field is presented in the context of recent electric dipole spin resonance experiments. We find that the spin-orbit coupling results in lifting the spin blockade by phonon mediated relaxation provided that the initially occupied state is close in energy to the ground state. This leads to suppression of the blockade from the triplet state with spins polarized parallel to the external magnetic field B. At higher B, after singlet-triplet ground-state transition a new channel for lifting the Pauli blockade opens which results in an appearance of additional resonance lines. The calculated signatures of this transition are consistent with recent experimental results [S. M. Frolov et al., Phys. Rev. Lett. 109, 236805 (2012)].