Thermoelectric Effect in a Correlated Quantum Dot Side-Coupled to Majorana Bound States

Feng Chi,Zhen-Guo Fu,Ping Zhang,Jia Liu,Ke-Man Li,Zhigang Wang

doi:10.1186/s11671-020-03307-y

Abstract

We theoretically study the thermoelectric effect in a hybrid device composed by a topological semiconducting nanowire hosting Majorana bound states (MBSs) and a quantum dot (QD) connected to the left and right non-magnetic electrodes held at different temperatures. The electron-electron Coulomb interactions in the QD are taken into account by the non-equilibrium Green’s function technique. We find that the sign change of the thermopower, which is useful for detecting the MBSs, will occur by changing the QD-MBS hybridization strength, the direct overlap between the MBSs at the opposite ends of the nanowire, and the system temperature. Large value of 100% spin-polarized or pure spin thermopower emerges even in the absence of Zeeman splitting in the QD or magnetic electrodes because the MBSs are coupled to electrons of only one certain spin direction in the QD due to the chiral nature of the Majorana fermions. Moreover, the magnitude of the thermopower will be obviously enhanced by the existence of MBSs.

Highlights

The preparation and detection of zero-energy Majorana bound states (MBSs) are of particular importance in modern condensed matter physics
The value of G↓, is almost unchanged even the occupation number n↓ is changed by λ1 due to the presence of intradot Coulomb interaction
In conclusion, we have studied the properties of the electrical conductance and thermopower in a quantum dot connected to the left and right normal metal electrodes with Coulomb interaction

Summary

Introduction

The preparation and detection of zero-energy Majorana bound states (MBSs) are of particular importance in modern condensed matter physics. (2020) 15:79 the hybridization of MBSs with other nanoscale structures, such as the zero-dimensional quantum dot (QD) in which the energy levels, electron-electron Coulomb interactions, particle numbers, and coupling strength to external environment are all well controllable [16, 17].

Results

Conclusion