Sequential and co-tunneling behavior in the temperature-dependent thermopower of few-electron quantum dots

TL;DR

This study investigates how thermopower oscillations in quantum dots change with temperature, revealing a crossover from sequential to cotunneling processes as temperature decreases.

Contribution

It provides experimental evidence of the temperature-dependent transition from sequential tunneling to cotunneling in quantum dot thermopower behavior.

Findings

Thermopower oscillations change shape with temperature.

A crossover from sequential to cotunneling is observed.

Cotunneling dominates at temperatures below 40 mK.

Abstract

We have studied the temperature dependent thermopower of gate-defined, lateral quantum dots in the Coulomb blockade regime using an electron heating technique. The line shape of the thermopower oscillations depends strongly on the contributing tunneling processes. Between 1.5 K and 40 mK a crossover from a pure sawtooth- to an intermitted sawtooth-like line shape is observed. The latter is attributed to the increasing dominance of cotunneling processes in the Coulomb blockade regime at low temperatures.