Speaker: Yung-Fu Chen, Frederick Seitz Materials Research Lab, UIUC
Abstract: Carbon nanotubes are considered model one-dimensional systems, and their electronic transport is strongly affected by electron-electron (e-e) interactions. Measurements of the non-equilibrium electron energy distribution function in nanotubes may directly determine electron energy relaxation rates, which may also tell us e-e scattering rates and therefore something about e-e interactions in nanotubes. We developed techniques to perform tunneling spectroscopy on nanotubes using non-invasive superconducting probes, which allows us to measure the shape of the electron energy distribution locally in nanotubes that have bias voltages applied between their ends to drive the electrons out of equilibrium. We find that at low temperatures electrons in nanotubes maintain their energy distribution across a few microns channel length. Surprisingly, the energy relaxation rate sometimes grows substantially when the temperature is raised to only 1.5 K.