Giant mesoscopic fluctuations of the elastic cotunneling thermopower of a single-electron transistor

TL;DR

This paper investigates the mesoscopic fluctuations of thermopower in a single-electron transistor within the elastic cotunneling regime, revealing that fluctuations are significantly larger than the average thermopower.

Contribution

It provides a theoretical analysis of the mesoscopic fluctuations of thermopower using random-matrix theory in a Coulomb blockade regime.

Findings

Thermopower fluctuations are much larger than the average value.

The study quantifies the statistical distribution of thermopower in the elastic cotunneling regime.

Transport coefficients depend strongly on impurity potential and island shape.

Abstract

We study the thermoelectric transport of a small metallic island weakly coupled to two electrodes by tunnel junctions. In the Coulomb blockade regime, in the case when the ground state of the system corresponds to an even number of electrons on the island, the main mechanism of electron transport at lowest temperatures is elastic cotunneling. In this regime, the transport coefficients strongly depend on the realization of the random impurity potential or the shape of the island. Using the random-matrix theory, we calculate the thermopower and the thermoelectric kinetic coefficient and study the statistics of their mesoscopic fluctuations in the elastic cotunneling regime. The fluctuations of the thermopower turn out to be much larger than the average value.