Interplay of Vibration and Coulomb Effects in Transport of Spin-Polarized Electrons in a Single-Molecule Transistor

TL;DR

This paper investigates how vibration and Coulomb effects influence spin-polarized electron transport in a single-molecule transistor, revealing staged Coulomb blockade lifting and doubled inelastic tunneling steps due to Zeeman splitting.

Contribution

It introduces a detailed analysis of vibrational and Coulomb interactions in spin-polarized transport, highlighting the doubling of Franck-Condon steps and non-monotonic conductance behavior.

Findings

Coulomb blockade is lifted in stages under magnetic field.

Franck-Condon steps are doubled due to Zeeman splitting.

Conductance exhibits non-monotonic temperature dependence.

Abstract

Tunnel transport of interacting spin-polarized electrons through a single-level vibrating quantum dot in external magnetic field is studied. By using density matrix method, the current-voltage characteristics and the dependence of conductance on temperature of a single-electron transistor were calculated. We found that a lifting of Coulomb blockade in external magnetic field happens in stages. The Franck-Condon steps associated with inelastic electron tunneling in our case are doubled due to contribution of two Zeeman-split levels in electron transport. The doubling of steps can be also observed in the presence of Coulomb interaction. For strong electron-vibron interaction the temperature dependence of conductance is shown to be non-monotonic and anomalous growth of conductance maximum weakly depends both on the Coulomb strength and the external magnetic field.