Graphene Trampolines and Vibrations

1. Graphene Trampolines and Vibrations Aron Pinczuk, Columbia University, DMR 0352738 Graphene, consisting of just a single sheet of carbon atoms, is the thinnest two-dimensional material. Amazingly, it can be prepared by peeling-off graphite using ‘Scotch’ tape, a process which unfortunately incorporates dirt, detrimental to its electronic properties Graphene trampoline, freely suspended from six gold electrodes Collapsed graphene, pulling with it six thick gold electrodes We have succeeded in suspending a single graphene sheet and cleaning it by annealing (top left figure). Electron transport in this graphene ‘trampoline’ has improved by a factor of 10, and is now largely limited by the sample size. Further advances are expected, once failure mechanisms such as layer collapse (right top figure) have been overcome. Raman spectroscopy is used to study graphene (lower left figure). The tunability of vibrations of carbon atoms by the gate voltage (lower right figure) uncover unique features linked to carriers participating in electrical conduction. Marked anomalies seen in vibration frequencies reveal fundamental physics and the impact of non-uniformity and dirt. Raman experiment. Two photons and a bilayer graphene are shown Spectra of vibrations showing high sensitivity to gate voltage

2. Graphene Trampolines and Vibrations Aron Pinczuk, Columbia University, DMR 0352738 Education: Four graduate students (Erik Henriksen, Trevor D. Rhone, Theresa Villarson and Jun Yan) and three postdocs (Dr. Yann Gallais, Dr. Javier Groshaus, and Dr. Kirill Bolotin) contribute to research supported by this NSF award. Altogether 4 undergraduate students are involved in the program and are sharing authorship ( Mason Jiang, Mollie Schwartz, Ken Sikes, Michael Shulman). Beyond exploring the frontiers of many particle quantum physics, students and postdocs are being trained in ultra low temperature techniques, semiconductor physics, material processing and clean-room methods. The expertise gained by the principle investigators flows into the physics curriculum at Columbia, where Pinczuk teaches condensed matter physics and Stormer teaches a university wide freshman class including nano-science and quantum mechanics. Societal Impact: Electronics of the future? The novel two-dimensional conductor graphene exhibits very unusual new physics. Yet it also is being considered as the basis for future electronic devices that may lead us beyond the limitations of the present technology. Our research helps laying the groundwork for such explorations. Columbia postdocs, graduate and undergraduate students working on graphene physics