Bi-stable tunneling current through a molecular quantum dot

TL;DR

This paper presents an exact solution for tunneling through a negative-U molecular quantum dot, revealing hysteresis and bi-stability in current due to electron correlations, with potential applications in molecular electronics.

Contribution

It provides an exact analytical model for bi-stable tunneling in negative-U molecular quantum dots, highlighting the role of degeneracy and electron correlations.

Findings

Hysteresis in tunneling current for d>2 degeneracy

Voltage-induced switching due to attractive electron correlations

Potential realization in fullerenes like C60

Abstract

An exact solution is presented for tunneling through a negative-U d-fold degenerate molecular quantum dot weakly coupled to electrical leads. The tunnel current exhibits hysteresis if the level degeneracy of the negative-U dot is larger than two (d>2). Switching occurs in the voltage range V1 < V < V2 as a result of attractive electron correlations in the molecule, which open up a new conducting channel when the voltage is above the threshold bias voltage V2. Once this current has been established, the extra channel remains open as the voltage is reduced down to the lower threshold voltage V1. Possible realizations of the bi-stable molecular quantum dots are fullerenes, especially C60, and mixed-valence compounds.