Suppression of spin relaxation in an InAs nanowire double quantum dot

TL;DR

This paper studies spin relaxation in InAs nanowire double quantum dots, revealing suppression at certain couplings and magnetic fields, and proposes a nuclear spin polarization model involving hyperfine and spin-orbit interactions.

Contribution

It introduces a detailed analysis of spin relaxation mechanisms and a model explaining bistability and relaxation suppression in InAs nanowire quantum dots.

Findings

Relaxation is minimized at intermediate coupling and finite magnetic field.

Bistability of spin-non conserving current is observed as a function of magnetic field.

Hyperfine and spin-orbit interactions interplay to polarize nuclear spins, affecting relaxation.

Abstract

We investigate the triplet-singlet relaxation in a double quantum dot defined by top-gates in an InAs nanowire. In the Pauli spin blockade regime, the leakage current can be mainly attributed to spin relaxation. While at weak and strong inter-dot coupling relaxation is dominated by two individual mechanisms, the relaxation is strongly reduced at intermediate coupling and finite magnetic field. In addition we observe a charateristic bistability of the spin-non conserving current as a function of magnetic field. We propose a model where these features are explained by the polarization of nuclear spins enabled by the interplay between hyperfine and spin-orbit mediated relaxation.