Interacting Two Dimensional Electron Systems

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Technical Abstract: This grant supports experimental condensed matter physics research aimed at the study of interacting electronic matter in two dimensions. The work focuses on two material systems: gallium arsenide-based semiconductor heterostructures grown by molecular beam epitaxy and graphene, a single atomic layer of carbon atoms. GaAs heterostructures have been intensely studied for several decades, and have yielded a vast trove of important fundamental physics and myriad technical applications. This grant enables further investigation of the remarkable excitonic Bose condensate which is realized in GaAs double quantum wells at high magnetic field, and crucial tests of the concept of excitonic superfluidity will be performed. In contrast to GaAs, graphene is quite new, having been isolated only six years ago. The advent of graphene sparked a firestorm of research owing to both its potential for technological application and its remarkable fundamental physics attributes. The grant enables a new set of experiments on graphene which focus on its thermodynamic and thermoelectric properties. In particular, the energy relaxation rates of the Dirac quasiparticles in graphene will be measured and a novel graphene hot-carrier thermocouple will be fabricated. The research enabled by this grant will contribute greatly to the education of graduate and undergraduate students and a postdoctoral associate. Non-technical Abstract: This grant supports basic research on advanced semiconductor materials, and on graphene, a single atomic layer of carbon. The aim is to improve the understanding of how large collections of electrons behave in such materials. The topics of greatest interest are those in which such collective behavior cannot be directly inferred from the detailed understanding of the properties of individual electrons. Such investigations are far from mere academic exercises. One hundred years ago superconductivity was discovered at such low temperatures that practically-minded citizens must have regarded it as a useless curiosity. Nowadays superconductivity is recognized to have revolutionized medical diagnostics by enabling magnetic resonance imaging (MRI). This grant allows experiments on an exotic form of quantum matter, known as an exciton condensate, whose properties resemble those of superconductors. How close the analogy is remains a key question. The grant also support experimentation on the thermal properties of graphene. This new material offers excellent prospects for new discoveries of both fundamental and applied significance. The research funded by this grant is executed by graduate and undergraduate students and a postgraduate associate. Thus this project has a strong educational component and will prepare these young scientists for sophisticated jobs within the Nation's technological base.