Current hysteresis and memory effect in a molecular quantum dot with strong electron-vibron interaction

TL;DR

This paper develops a theoretical model explaining current hysteresis and memory effects in a molecular quantum dot with strong electron-vibron interactions, revealing bistability and switching phenomena in current-voltage behavior.

Contribution

It introduces a model for a degenerate molecular quantum dot with strong electron-vibron coupling, demonstrating bistability and hysteresis consistent with negative-U models.

Findings

Identification of bistable current states below a critical temperature.

Prediction of switching behavior in current-voltage characteristics.

Agreement with phenomenological negative-U models.

Abstract

Theory of current hysteresis for tunneling through a molecular quantum dot (MQD) with strong electron-vibron interactions and attractive electron-electron correlations is developed. The dot is modeled as a d-fold degenerate energy level weakly coupled to the leads. The effective attractive interaction between polarons in the dot results in a "switching" phenomenon in the current-voltage characteristics when d>2, in agreement with the results for the phenomenological negative-U model. The degenerate MQD with strong electron-vibron coupling has two stable current states in certain interval of the bias voltage below some critical temperature.