Graphene-based allotropes such as carbon nanorings hold the promise of completely new nanodevice and metamaterials applications due to the effects of magnetic flux and curvature on quantum transport on a nanoscale toroidal surface and the coherence of resulting electromagnetic moments. Modular symmetries due to rolling the flat graphene sheet to a two-dimensional manifold with toroidal geometry are predicted to significantly impact energy band structure and transport properties of physically distinct nanotori with different chiralities and dimensions. In addition to persistent current and Aharonov-Bohm effects under magnetic flux, new magnetic moments such as a new toroidal moment will be generated by the ring currents. In a metamaterial of these aligned nanoconstituents a significant enhancement of these quantum signatures may be expected due to coherence of the individual electromagnetic responses. In a first step, electron transport on a carbon nanotorus is calculated in a tightbinding model for armchair and zigzag carbon nanotori between metallic leads using a recursive non-equilibrium Green's function method. Density-of-states, transmission function and the integrated source drain current can be calculated for realistic system sizes of 10,000 carbon atoms and more. A fast and numerically precise parallel software tool has been developed on a multi-core architecture that can incorporate additional effects such as electron-phonon coupling effects due to low-energy phonon modes, exciton transport, or electron-plasmon coupling terms in second- or third-nearest-neighbor type calculations.

Short Bio:
Dr. Mark Jack is associate professor at Florida A&M University’s Physics Department in Tallahassee, FL. He completed his Ph.D. in theoretical particle physics at the Humboldt Universität Berlin, Germany in 2000 on fermion-pair production at the CERN/LEP2 experiment and for linear collider physics. He was postdoc at UCLA’s Neurobiology Department from 2000 to 2002 investigating spike-train statistics in mice retinal ganglion cells due to natural visual stimuli. In 2003 he joined the faculty at Florida A&M University’s Ph.D. program in physics and has focused in his research on theory and simulation of quantum charge transport in carbon nanostructures and -devices. His current research interests are in the area of metamaterials, nanoplasmonics, organic photovoltaic materials and large-scale quantum transport simulations via high-performance computing. He is currently on sabbatical leave at the University of Central Florida’s NanoScience Technology Center and Physics Department. More information can be found at: http://www.famu.edu/index.cfm?DepartmentofPhysics&AboutPhysics