Fano-Rashba effect in thermoelectricity of a double quantum dot molecular junction

Ys Liu,Jf Feng,Xf Yang,Xk Hong

doi:10.1186/1556-276x-6-618

Ys Liu, Jf Feng + Show 2 more

Open Access

https://doi.org/10.1186/1556-276x-6-618

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Abstract

We examine the relation between the phase-coherent processes and spin-dependent thermoelectric effects in an Aharonov-Bohm (AB) interferometer with a Rashba quantum dot (QD) in each of its arm by using the Green's function formalism and equation of motion (EOM) technique. Due to the interplay between quantum destructive interference and Rashba spin-orbit interaction (RSOI) in each QD, an asymmetrical transmission node splits into two spin-dependent asymmetrical transmission nodes in the transmission spectrum and, as a consequence, results in the enhancement of the spin-dependent thermoelectric effects near the spin-dependent asymmetrical transmission nodes. We also examine the evolution of spin-dependent thermoelectric effects from a symmetrical parallel geometry to a configuration in series. It is found that the spin-dependent thermoelectric effects can be enhanced by controlling the dot-electrode coupling strength. The simple analytical expressions are also derived to support our numerical results.PACS numbers: 73.63.Kv; 71.70.Ej; 72.20.Pa

Highlights

We note that most of the spin Seebeck effects are obtained by using ferromagnetic materials such as ferromagnetic thin films, ferromagnetic semiconductors, or ferromagnetic electrodes et al In our previous work, a pure spin generator consisting of a Rashba quantum dot molecule sandwiched between two non-ferromagnetic electrodes via Rashba spin-orbit interaction (RSOI) instead of ferromagnetic materials has been proposed by the coaction of the magnetic flux [24]
We investigate the spin-dependent thermoelectric effects of parallel-coupled double quantum dots embedded in an AB interferometer, in which the RSOI in each QD is considered by introducing a spin-dependent phase factor in the linewidth matrix elements
We examine the evolution of spin-dependent Seebeck effects from a symmetrical parallel geometry to a configuration in series

Summary

Introduction

With the fast development and improvement of experimental techniques [1,2,3,4,5,6,7,8,9], much important physical properties in QD molecules such as electronic structures, electronic transport, and thermoelectric effects et al have widely attracted academic attention [10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]. We note that most of the spin Seebeck effects are obtained by using ferromagnetic materials such as ferromagnetic thin films, ferromagnetic semiconductors, or ferromagnetic electrodes et al In our previous work, a pure spin generator consisting of a Rashba quantum dot molecule sandwiched between two non-ferromagnetic electrodes via RSOI instead of ferromagnetic materials has been proposed by the coaction of the magnetic flux [24]. We investigate the spin-dependent thermoelectric effects of parallel-coupled double quantum dots embedded in an AB interferometer, in which the RSOI in each QD is considered by introducing a spin-dependent phase factor in the linewidth matrix elements. We consider the quantum system in the linear response regime such as an infinitesimal temperature gradient ΔT raised in the right metallic electrode, which will induce an infinitesimal spin-dependent thermoelectric voltage ΔVs since the two tunneling channels related to spin are opened. The phonon thermal conductance of the junction, which is typically limited by the QDs-electrode contact, has been ignored in the case of the poor link for phonon transport

Results and discussion

30. Fano U

32. Rashba EI