Molecular electronics and non-equilibrium physics

Electronic transport through single molecules and molecular thin films is interesting both for possible applications and from a fundamental physics point of view. So far, we have mainly studied molecule-based transistors containing magnetic molecules, for example in transition-metal ions. Here, the strong coupling between the tunneling electrons and the local spins in the molecule leads to characteristic signatures in the current-voltage characteristics. We have predicted new effects such as giant spin amplification: The total magnetic moment deposited in the electrodes due to spin-dependent tunneling through a magnetic molecule can be several orders of magnitude larger than the molecular magnetic moment. We are working both on methodological progress in the description of transport far from equilibrium and on quantitative modeling of specific devices. Our method of choice is the quantum master equation.

Another research direction concerns electronic tunneling through an interacting molecular monolayer. This system can be mapped onto an Ising-type model far from equilibrium. Among other results, we find current-induced charge order. We also study one-dimensional molecular chains.