Understanding Kondo Peak Splitting and the Mechanism of Cohernt Transport in a Single-Electron Transistor

TL;DR

This paper explains the splitting of the Kondo peak under magnetic fields and bias in single-electron transistors by calculating nonequilibrium Green's functions, revealing new resonant levels and mechanisms of coherent transport.

Contribution

It introduces a nonperturbative dynamical theory approach to analyze Kondo peak splitting and identifies the activation of new resonant tunneling levels near the Fermi level.

Findings

New resonant tunneling levels are activated near the Fermi level.

Magnetic field causes asymmetry and transforms the resonant peaks.

The mechanism of coherent transport through the new levels is explained.

Abstract

The peculiar behavior of Kondo peak splitting under a magnetic field and bias can be explained by calculating the nonequilibrium retarded Green's function via the nonperturbative dynamical theory (NDT). In the NDT, the application of a lead-dot-lead system reveals that new resonant tunneling levels are activated near the Fermi level and the conventional Kondo peak at the Fermi level diminishes when a bias is applied. Magnetic field causes asymmetry in the spectral density and transforms the new resonant peak into a major peak whose behavior explains all the features of the nonequilibrium Kondo phenomenon. We also show the mechanism of coherent transport through the new resonant tunneling level.