Nanoscale Physics

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My research program is directed at obtaining a fundamental understanding of the physics of nanostructures, systems with dimensions ranging from about a nanometer to a few hundred nanometers. Nanostructures have properties that differ from those of both individual atoms and macroscopic everyday objects. Their importance for applications ranging from information processing to medicine is widely recognized. The proposed research will have a number of foci within this general theme: We will build on our previous successes elucidating the transport properties of graphene nanostructures, including nanoribbons of carbon atoms several nanometers wide and a single atomic layer thick. We will take this research in a new direction, prompted by the recent surprising experimental discovery that some graphene nanoribbons as long as 16 micrometers on SiC substrates exhibit conductances near e2/h up to room temperature. We will investigate possible mechanisms (including ferromagnetism, structural strains, enhanced spin-orbit coupling due to interactions with the SiC, and topological protection) that may give rise to this as yet unexplained effect. We will extend this research further to transition metal dichalcogenide nanostructures whose strong spin-orbit coupling may result in topologically protected electronic and spintronic properties. There is currently orders of magnitude disagreement between many experiments probing spin injection from ferromagnets into semiconductors and theory. We will carry out computer simulations to resolve this fundamental conflict. We will continue our theoretical studies of single-molecule nanomagnets that may find applications as high density magnetic memories or in quantum information processing. Experimentalists have recently begun to successfully insert single-molecule magnets into electric circuits putatively without damaging the molecule, and measuring the transport properties of the resulting devices. The new experimental data will help us develop realistic fundamental theories of charge and spin transport through single molecule nanomagnet transistors. We will also continue our work aimed at understanding the interfaces between the molecule and electrodes in single-molecule electronic and spintronic devices. This effort is aimed at gaining atomic scale control of the structures of these interfaces which is needed for practical device applications as well as for definitively benchmarking theories of transport in these systems against experiment. The proposed research is expected to achieve a better understanding of novel nanoscale systems and will train students and postdocs to do pioneering fundamental theoretical research closely linked to cutting edge experiments in nanoscience, a field of huge and rapidly growing scientific and technological importance. It may facilitate creation of new technologies that benefit Canada.