Stationary and transient leakage current in the Pauli spin blockade

TL;DR

This paper investigates how cotunneling and non-uniform Zeeman splitting influence stationary and transient leakage currents in a double quantum dot under Pauli spin blockade, revealing conditions for pure spin state preparation and methods to probe spin relaxation.

Contribution

It introduces a detailed analysis of cotunneling effects and fractional effective charge as tools for understanding spin dynamics in quantum dots.

Findings

Cotunneling current vanishes at low temperature and high magnetic field.

Fractional effective charge $e^*$ characterizes current between blockade events.

Pure spin ground state can be prepared dynamically under certain conditions.

Abstract

We study the effects of cotunneling and a non-uniform Zeeman splitting on the stationary and transient leakage current through a double quantum dot in the Pauli spin blockade regime. We find that the stationary current due to cotunneling vanishes at low temperature and large applied magnetic field, allowing for the dynamical preparation of a pure spin ground state, even at large voltage bias. Additionally, we analyze current that flows between blocking events, characterized, in general, by a fractional effective charge $e^*$. This charge can be used as a sensitive probe of spin relaxation mechanisms and can be used to determine the visibility of Rabi oscillations.