Date: Tuesday, May 19, 2015
Time: 11:00 am
Speaker: Doug Natelson, Rice University
Title: Vibrational and Electronic Heating in Atomic-Scale Junctions
Location: 67-3111 Chemla Room
My research group focuses on the electronic, magnetic, and (recently) optical properties of nanoscale structures. Over the last twenty years there has been tremendous progress in the ability to manipulate matter at levels approaching the atomic scale. By constructing model nanosystems (nanoparticle, nanowires, atomic-scale junctions, transistors with individual molecules as the active region), we are able to examine the basic physics that becomes relevant at these scales. Effects that can be important at the nanoscale include:
Quantum coherence - Electrons are quantum mechanical objects, and quantum effects clearly dominate at the atomic scale; however, you never worry about quantum interference when you turn on the lights. Nanoscale systems allow us to examine the crossover between quantum and classical behavior, and the processes that lead to this decoherence.
Quantum confinement - Constraining electrons to occupy a smaller and smaller volume forces their energy levels farther apart. In very small systems, the level spacing can greatly exceed the available thermal energy even at room temperature, leading to interesting and potentially useful effects.
Near-field optical effects - In the presence of light, the local optical intensity near nanoscale objects can be very different than the incident intensity. In some circumstances nanosystems can act like optical antennas, leading to dramatic changes in optical properties.
Strong correlations - Often in condensed matter physics we can get away with ignoring electron-electron interactions. However this is not always a good idea, and many important physical systems (e.g., the high temperature superconductors, many transition metal oxides) electron-electron interactions lead to major consequences (insulating states, magnetism, superconductivity). In nanostructures, when electrons can be forced into close proximity, we can make tunable models with which to examine strong electronic correlations.
Specific research topics include: atomic- and molecular-scale electronic devices; organic semiconductor systems; single-molecule optical measurements; and nanostructures incorporating strongly correlated materials. Recent publications are available at our group homepage.
In addition to learning a lot of neat physics, people in this research group will develop skills in micro- and nanofabrication, sensitive electrical measurements,various microscopy techniques, low temperature physics, and vacuum systems.