While such electronic phases have been thoroughly studied in GaAs two-dimensional electron gas, their observation in graphene has been limited by disorder, potential fluctuations being larger than the FQH gaps in most devices. At high magnetic field, this yields a variety of new incompressible phases known as fractional quantum Hall (FQH) states. With kinetic energy quenched, electron interactions determine the ground state of a partially filled Landau level. In a large magnetic field B, the band structure of two dimensional electrons becomes a discrete set of highly degenerate Landau levels. Integer and Fractional Quantum Hall effect The whole structure rests on an oxidized silicon wafer.ġ. 1: Schematic of a graphene on boron nitride device with a graphite back-gate. This device quality allows us to study a variety of exotic electronic phenomena.įig. The resulting heterostructures can have carrier mobilities of at least 400 000 cm 2/Vs at low temperature, which corresponds to mean free paths of several microns. We stack these flakes into van der Waals heterostructures. Hexagonal boron nitride is an insulator with a crystal structure similar to that of graphite that can also be exfoliated into thin, atomically flat flakes. We use hexagonal boron-nitride as a gate dielectric and an encapsulating material. As a result, low-energy quasiparticles are massless and described by the Dirac equation, which results in a wide variety of exotic electronic phenomena, such as Klein tunneling and a zeroth landau level. At low energy, the band-structure of graphene has a linear dispersion relation, different from the usual quadratic dispersion of the valence and conduction bands in regular semiconductors. Our group studies the electronic properties of graphene, a one atom thick carbon crystal with a honeycomb lattice. Contact Aaron Sharpe or Derrick Boone for more information.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |