Quantum dot as spin current generator and energy harvester

Barbara Szukiewicz,Karol I Wysokiński

doi:10.1140/epjb/e2015-60156-8

Barbara Szukiewicz, Karol I Wysokiński

Open Access

https://doi.org/10.1140/epjb/e2015-60156-8

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Abstract

The thermoelectric transport in the device composed of a central nanoscopic system in contact with two electrodes and subject to the external magnetic field of Zeeman type has been studied. The device can support pure spin current in the electrodes and may serve as a source of the temperature induced spin currents with possible applications in spintronics. The system may also be used as an energy harvester. We calculate its thermodynamic efficiency η and the power output P. The maximal efficiency of the device reaches the Carnot value when the device works reversibly but with the vanishing power. The interactions between carriers diminish the maximal efficiency of the device, which under the constant load drops well below the Carnot limit but may exceed the Curzon-Ahlborn limit. While the effect of intradot Coulomb repulsion on η depends on the parameters, the interdot/interlevel interaction strongly diminishes the device efficiency.

Highlights

The desire to find materials and/or structures with a high thermoelectric performance is the driving force of material science and nanotechnology [1,2] and is vital for efficient energy harvesters or refrigerators
In the systems which do not obey Wiedemann-Franz law the diminition of the thermal conductivity [4] κ and the Lorentz number L is often crucial to achieve large ZT
Dubi and Di Ventra’s proposal [12] to get pure spin current in a device consisting of a quantum dot in an external B field has stimulated a great deal of work in that direction [13,14]

Summary

Introduction

The desire to find materials and/or structures with a high thermoelectric performance is the driving force of material science and nanotechnology [1,2] and is vital for efficient energy harvesters or refrigerators. Dubi and Di Ventra’s proposal [12] to get pure spin current in a device consisting of a quantum dot in an external B field has stimulated a great deal of work in that direction [13,14]. Similar systems consisting of a single or double quantum dot have been extensively studied with the aim to find configurations with enhanced Seebeck coefficient Sc or thermoelectric figure of. This allows identification of the regions with huge values of ZT and large value of ηZT for subsequent comparision with η calculated outside the linear regime.

The model and approach

Linear response

Quantum dot as a thermoelectric power generator

Summary and conclusions