| speaker: | Douglas Natelson Rice University, USA |
| time: | Mo., 20.08, 11:20-12:10 |
In semiconductor quantum dots, the Kondo temperature has been observed to depend exponentially on the gate voltage. This dependence arises because in these structures the gate capacitively shifts the energy of the singly-occupied Kondo-active level relative to the chemical potential of the conduction electrons in the source and drain. In single-molecule transistors incorporating transition metal complexes, we find that the expected gate dependence in the Kondo regime is not observed. While the data show that the gate does shift electronic levels, the Kondo temperature found from both the differential conductance temperature and bias voltage dependence is approximately independent of gate voltage. We discuss possible explanations for this surprising observation, including the possible effect of molecular vibrational modes. We will also discuss other ongoing measurements to probe strong correlation effects in these unique nanostructures.