Coulomb and Spin blockade of two few-electrons quantum dots in series in the co-tunneling regime

TL;DR

This study investigates Coulomb and spin blockade phenomena in a two-electron quantum dot system in series, revealing how co-tunneling and charge redistribution events influence current modulation.

Contribution

The paper demonstrates how spin blockade and charge redistribution can be detected via co-tunneling in a double quantum dot system with one dot off-resonance.

Findings

Current amplitude modulation reflects spin blockade events.

Charge redistribution in off-resonance dot affects the aligned dot's electrochemical potential.

Co-tunneling enables charge transfer despite off-resonance conditions.

Abstract

We present Coulomb Blockade measurements of two few-electron quantum dots in series which are configured such that the electrochemical potential of one of the two dots is aligned with spin-selective leads. The charge transfer through the system requires co-tunneling through the second dot which is $not$ in resonance with the leads. The observed amplitude modulation of the resulting current is found to reflect spin blockade events occurring through either of the two dots. We also confirm that charge redistribution events occurring in the off-resonance dot are detected indirectly via changes in the electrochemical potential of the aligned dot.