Bi-stability in single impurity Anderson model with strong electron-phonon interaction (polaron regime)

TL;DR

This paper investigates a single impurity Anderson model with strong electron-phonon coupling, revealing bi-stability, hysteresis, and negative differential conductance in the I-V characteristics due to effective electron-electron attraction.

Contribution

It demonstrates that strong electron-phonon interactions induce bi-stability and hysteresis in the non particle-hole symmetric regime of the SIAM, a novel insight into polaron effects.

Findings

Bi-stability appears with strong electron-phonon coupling.

Hysteresis loop observed in I-V characteristics.

Negative differential conductance occurs at certain bias voltages.

Abstract

We consider a single impurity Anderson model (SIAM) in which the quantum dot(QD) is strongly coupled to a phonon bath in polaron regime. This coupling results in an effective e-e attraction. By computing the self energies using a current conserving approximation which is up to second order in this effective attraction, we show that if the interaction is strong enough, in non particle-hole(PH) symmetric case, the system would be bi-stable and we have hysteresis loop in the I-V characteristic. Moreover, the system shows negative differential conductance in some bias voltage intervals.