Secondary Coulomb Blockade Gap in a Four-Island Tunnel-Junction Array

TL;DR

This paper investigates the secondary Coulomb blockade gap in a four-island tunnel-junction array, revealing how its topology causes electron trapping and affects tunneling behavior, including negative differential resistance.

Contribution

It introduces the concept of a secondary Coulomb blockade gap in a four-island array and analyzes its formation and destruction through detailed tunneling process modeling.

Findings

Secondary Coulomb blockade gap observed in I-V characteristics.

Topology induces electron trapping leading to the gap.

Negative differential resistance occurs with fluctuations.

Abstract

In the ring-shaped tunnel-junction array with four islands, the secondary Coulomb blockade gap in a low bias-voltage range is observed in the I-V characteristics. We attribute its appearance to the unique topology of the array which induces up to two electrons to get trapped inside. We have analyzed the formation and destruction of the gap in terms of detailed single-electron tunneling processes. The negative differential resistance behavior when the thermal and quantum fluctuations are present is also studied.