Michelle Simmons Ph.D.
I am interested in the study of interaction effects in ultra-high quality one and two dimensional single electron and hole gases in the GaAs/AlGaAs material system. These interaction effects give rise to phenomenon such as Luttinger liquid behaviour, Wigner crystallisation and the forbidden metal-insulator transition in high quality 2D systems. Recently I have been studying the metallic state in ultra high quality 2D hole systems in the GaAs/AlGaAs material system. Preliminary transport studies of very low density gated single layer hole gas samples showed that as the carrier density was increased from a highly correlated, possibly Wigner crystal, insulating state a transition at rs=26 to a metallic state was observed. This was the first observation of a novel and unexpected 2D metallic state in GaAs hole systems and at the time was important since it confirmed that the metallic state was a universal property of highly correlated 2D systems.This work was extended to look at the presence of scaling behaviour of the resistivity of 2D hole gases where it was shown that as the temperature tended to zero Kelvin the resistivity in the metallic phase tended towards a finite value indicating a true phase transition rather than a finite temperature effect. The metallic state has only been observed in pure, highly correlated 2D systems. Theoretically it has been predicted that if the interactions could be switched off in some way then the metallic phase would disappear. New samples were designed to test this theory and our latest results have confirmed that there is a re-entrant insulator-metal-insulator transition as the interaction strength is reduced. At the University of New South Wales I will continue to look at highly correlated electron and hole systems and will also join the quantum computation team to look at highly correlated nuclear spin systems. My expertise in UHV and MBE systems will help with the inital fabrication stages of the two qubit quantum computer test device. Whilst at the Cavendish Laboratory in Cambridge I was in charge of a Varian Gen II MBE growth facility, which was used to produce ultra-high quality GaAs/AlGaAs two-dimensional electron and hole gas heterostructures. The table of typical samples below gives details of some of the single and bilayer electron and hole gases that I designed and highlights the research areas that I was involved in. . EducationPhD. (1988-91) Durham University, UK; PostDoc. (1992-98) Cambridge University, UKBooksNanotechnology: Basic Science and Emerging Technologies |
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