Abstract
We investigate the thermopower of single molecules weakly coupled to metallic leads. We model the molecule in terms of the relevant electronic orbitals coupled to phonons corresponding to both internal vibrations and to oscillations of the molecule as a whole. The thermopower is computed by means of rate equations including both sequential-tunneling and cotunneling processes. Under certain conditions, the thermopower allows one to access the electronic and phononic excitation spectrum of the molecule in a linear-response measurement. In particular, we find that the phonon features are more pronounced for weak lead-molecule coupling. This way of measuring the excitation spectrum is less invasive than the more conventional current-voltage characteristic, which, by contrast, probes the system far from equilibrium.
| Original language | English (US) |
|---|---|
| Article number | 195107 |
| Pages (from-to) | 1-12 |
| Number of pages | 12 |
| Journal | Physical Review B - Condensed Matter and Materials Physics |
| Volume | 70 |
| Issue number | 19 |
| DOIs | |
| State | Published - Nov 2004 |
Funding
The authors thank I. Bar-Joseph for suggesting an investigation of thermoelectric effects in single-molecule devices and C. Timm for useful discussions. Two of the authors (F.v.O. and J.K.) thank the Weizmann Institute for hospitality (supported through the LSF and the Einstein Center). This work was supported in part by SFB 290, the Junge Akademie (F.v.O.), as well as the Minerva Foundation, and DIP under Grant No. C-7.1 (Y.O.).
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics