Transport through a quantum dot subject to spin and charge bias: Kondo regime

TL;DR

This paper theoretically investigates spin and charge transport through a quantum dot under spin and charge bias, focusing on the Kondo effect and how external biases and electron-phonon interactions influence conductance features.

Contribution

It introduces a detailed non-equilibrium Green function analysis of the Kondo regime in quantum dots with spin and charge biases, including electron-phonon effects.

Findings

Zero-bias Kondo anomaly in spin conductance splits under magnetic or charge bias.

Distinct behavior observed in mixed charge/spin conductance.

Electron-phonon coupling affects tunneling current and conductance.

Abstract

Spin and charge transport through a quantum dot coupled to external nonmagnetic leads is analyzed theoretically in terms of the non-equilibrium Green function formalism based on the equation of motion method. The dot is assumed to be subject to spin and charge bias, and the considerations are focused on the Kondo effect in spin and charge transport. It is shown that the differential spin conductance as a function of spin bias reveals a typical zero-bias Kondo anomaly which becomes split when either magnetic field or charge bias are applied. Significantly different behavior is found for mixed charge/spin conductance. The influence of electron-phonon coupling in the dot on tunneling current as well as on both spin and charge conductance is also analyzed.