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Jeudi 25 juin
The experimental observation of the Quantum Hall (QH) effect in single atomic sheet of graphene has attracted much attention recently, particularly due to the unique analogy to quasi relativistic quantum mechanics in its electronic structures.
Compared with the conventional integer QH effect in many other twodimensional (2D) systems, the filling factor quantization condition in graphene is shifted by a half integer at relatively low magnetic fields. At the extreme quantum limit, additional QH states corresponding lifting of the four-fold degeneracy of the lowest Landau level (LL) appear. The nature of these QH states near the charge neutral Dirac point is of fundamental interest as a single particle theory breaks down. In this talk, we will discuss the transport and IR measurement results that reveal the role of the many-body effects due to the electron-electron interaction in graphene near the Dirac point. In addition, we will discuss the conductance oscillations in extremely narrow graphene heterostructures
where a resonant cavity is formed between two electrostatically created bipolar junctions.