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Résumé |
In a series of experiment on 2D electron gas at the surface of Bi, we have been able to probe a number of
novel features of quantum Hall liquids for the first time. First, we have been able to use the scanning
tunneling microscope (STM) to directly visualize Landau orbits in real space. This new technique has been
used to show that the electronic states associated with the valley state on the surface of Bi form nematic
quantum Hall liquids. By tuning the magnetic field, we have been able to stabilize different type nematic
fluids, and have been able uncover a ferroelectric quantum Hall liquid that forms when only one of the valley
gets occupied. We are able to demonstrate that the formation of these valley polarized states quantum Hall
phases are driven by electron-electron interaction. Finally, in the most recent experiment, we have been able
to uncover domain walls between different nematic quantum Hall states and to direct image the 1D Luttinger
liquids that form at such interfaces. This new type of Luttinger liquids can become metallic or insulating
depending on the number of valley-textured edge modes, which can be understood by considering how valley
flavor constrain Coulomb interaction. In addition to these experiments, I will describe proposed efforts based
on these experiments in trying to use the STM to probe anyons in fractional quantum phases.
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