Thermoelectric transport through a T-shaped DQD connected to ferromagnetic and superconducting electrodes

Li Xu,Zhi-Jian Li,Yi-Hang Nie,Qiang Wang

doi:10.1063/1.4971844

Li Xu, Zhi-Jian Li + Show 2 more

Open Access

https://doi.org/10.1063/1.4971844

Copy DOI

Abstract

We theoretically analyze the properties of thermoelectric transport through a T-shaped DQD connected to ferromagnetic and superconducting electrodes by means of nonequilibrium Green function formalism. The influences of the superconducting gap, interdot tunneling coupling and asymmetry parameter on the thermoelectric properties are discussed. The large thermoelectric efficiency can be obtained by choosing small polarization of ferromagnetic electrode, small asymmetry parameter (&lt;1), appropriately large gap and appropriately interdot coupling, which can be used as the optimal schemes for obtaining high thermoelectric efficiency in the device.

Highlights

We introduce a new dimensionless parameter φ = ΓL0/ΓR0 which describes the asymmetry of coupling strength of the QD1 and two electrodes
We have studied the properties of thermoelectric transport through a T-shaped DQD connected to ferromagnetic and superconducting electrodes, and discussed the influences of the superconducting gap, interdot tunneling coupling and asymmetry parameter on the thermoelectric properties
For the case of the interdot coupling vanishing, in a limited range of the gap the thermopower increases with the gap increasing due to the electric conductance decreasing, corresponding effective figure of merit increases with the gap

Summary

INTRODUCTION

With the development of nanotechnology, several kinds of hybrid mesoscopic structures have been realized experimentally, for example, a quantum dot (QD) coupled to normal (N), ferromagnetic (F) and superconducting (S) electrodes.[1,2,3,4,5] Electronic transport through these hybrid mesoscopic structures exhibits rich physics and potential applications in spintronics.[5,6,7,8] The quantum interference effect, which is formed by the different paths of electron waves in hybrid mesoscopic system, is one of the main features of fundamental physics,[8,9,10,11,12] such as Aharonov-Bohm (A-B) effect, Fano effect, Dicke effect and so on. Superconducting electrodes and investigated the influences of the superconducting gap, interdot tunneling coupling and asymmetry parameter on the thermoelectric properties of the device. We analyze the role of quantum interference, Andreev reflection and single electron tunneling in the thermoelectric transport through the device.

PHYSICAL MODEL AND FORMULA DERIVATION

RESULTS AND DISCUSSION

Effect of interdot tunneling coupling t

Effect of the asymmetry

CONCLUSION