Measuring the phonon-assisted spectral function by using a non-quilibrium three-terminal single-molecular device

TL;DR

This study proposes a three-terminal single-molecular transistor setup as an experimental tool to accurately measure the phonon-assisted spectral function by analyzing differential conductance, with robustness at low temperatures.

Contribution

It demonstrates that the differential conductance of the third terminal can directly reflect the phonon-assisted spectral function, providing a new method for spectral analysis in molecular devices.

Findings

Matching between conductance and spectral function is accurate under certain conditions.

The matching persists at low temperatures regardless of bias.

High temperatures disrupt the conductance-spectral function correspondence.

Abstract

The electron transport through a three-terminal single-molecular transistor (SMT) is theoretically studied. We find that the differential conductance of the third and weakly coupled terminal versus its voltage matches well with the spectral function versus the energy when certain conditions are met. Particularly, this excellent matching is maintained even for complicated structure of the phonon-assisted side peaks. Thus, this device offers an experimental approach to explore the shape of the phonon-assisted spectral function in detail. In addition we discuss the conditions of a perfect matching. The results show that at low temperatures the matching survives regardless of the bias and the energy levels of the SMT. However, at high temperatures, the matching is destroyed.