Coulomb Blockade of a Three-terminal Quantum Dot

TL;DR

This paper investigates the Coulomb blockade phenomena in a three-terminal quantum dot setup, analyzing electron-hole asymmetry and cotunneling effects with both metallic and ferromagnetic leads to enhance understanding beyond traditional two-terminal systems.

Contribution

It introduces a detailed analysis of three-terminal quantum dots, including cotunneling regularization and comparison between metallic and ferromagnetic leads, providing new insights into electron transport mechanisms.

Findings

Current through the stem reflects electron-hole asymmetry.

Cotunneling contributions are significant at charge degeneracy points.

Three-terminal setup offers additional information over two-terminal configurations.

Abstract

We study an interacting single-level quantum dot weakly coupled to three electrodes. When two electrodes are biased by voltages with opposite polarities, while keeping the third lead (the stem) grounded, the current through the stem is a measure of electron-hole asymmetry of the dot. In this setup we calculate the stem current for both metallic and ferromagnetic (collinearly polarized) leads and discuss how the three-terminal device gives additional information compared to the usual two-terminal setup. We calculate both the sequential and cotunneling contribution for the currents. For the latter part we include a regularization procedure for the cotunneling current, which enables us to also describe the behavior at the charge degeneracy points.