Co-tunneling spin blockade observed in a three-terminal triple quantum dot

TL;DR

This study demonstrates Pauli spin blockade in a three-terminal triple quantum dot system, revealing how inter-dot coupling and the third dot influence co-tunneling and spin blockade phenomena.

Contribution

It introduces a three-terminal triple quantum dot setup to observe and analyze Pauli spin blockade and co-tunneling effects, highlighting the role of the third dot in these processes.

Findings

Pauli spin blockade observed in triple quantum dots.

Co-tunneling suppression due to spin blockade in strong coupling.

Resonant coupling and spin exchange lift the blockade.

Abstract

We prepare a triple quantum dot with a separate contact lead to each dot to study Pauli spin blockade in the tunnel-coupled three dots in a row. We measure the tunneling current flowing between the center dot and either the left or right dot with the left and right leads as a common source and the center lead as a drain. In the biased stability diagram, we establish Pauli spin blockade in the respective neighboring dots, with features similarly obtained in double quantum dot systems. We further realize Pauli spin blockade with two different conditions by tuning the inter-dot coupling gates: strong and weak inter-dot tunnel coupling regimes. In the strong-coupling regime we observe significant suppression of co-tunneling through the respective double dots due to Pauli spin blockade. We reveal the influence from the third dot in the triple dot device on this co-tunneling Pauli spin blockade and clarify that the co-tunneling Pauli spin blockade is lifted by the resonant coupling of excited states to the third dot level as well as spin exchange of the left and right dots with the adjacent reservoir.