Kenji Watanabe

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We report observation of the fractional quantum Hall effect (FQHE) in high mobility multi-terminal graphene devices, fabricated on a single crystal boron nitride substrate. We observe an unexpected hierarchy in the emergent FQHE states that may be explained by strongly interacting composite Fermions with full SU(4) symmetric underlying degrees of freedom.(More)
We report on a capacitance study of dual gated bilayer graphene. The measured capacitance allows us to probe the electronic compressibility as a function of carrier density, temperature, and applied perpendicular electrical displacement D. As a band gap is induced with increasing D, the compressibility minimum at charge neutrality becomes deeper but remains(More)
Electronic systems with multiple degenerate degrees of freedom can support a rich variety of broken symmetry states. In a graphene Landau level (LL), strong Coulomb interactions and the fourfold spin–valley degeneracy lead to an approximate SU(4) isospin symmetry. At partial filling, exchange interactions can break this symmetry, manifesting as further Hall(More)
The rotenone sensitivity of bovine heart NADH: coenzyme Q oxidoreductase (Complex I) depends significantly on coenzyme Q1 concentration. The rotenone-insensitive Complex I reaction in Q1 concentration range above 300 microM indicates an ordered sequential mechanism with Q1 and reduced Q1 (Q1H2) as the initial substrate to bind to the enzyme and the last(More)
Steady-state kinetics of the bovine heart NADH:coenzyme Q oxidoreductase reaction were analyzed in the presence of various concentrations of NADH and coenzyme Q with one isoprenoid unit (Q1). Product inhibitions by NAD+ and reduced coenzyme Q1 were also determined. These results show an ordered sequential mechanism in which the order of substrate binding(More)
We report on the fabrication and measurement of a graphene tunnel junction using hexagonal-boron nitride as a tunnel barrier between graphene and a metal gate. The tunneling behavior into graphene is altered by the interactions with phonons and the presence of disorder. We extract properties of graphene and observe multiple phonon-enhanced tunneling(More)
Uniaxial materials whose axial and tangential permittivities have opposite signs are referred to as indefinite or hyperbolic media. In such materials, light propagation is unusual leading to novel and often non-intuitive optical phenomena. Here we report infrared nano-imaging experiments demonstrating that crystals of hexagonal boron nitride, a natural(More)
Two-dimensional crystals such as graphene and transition-metal dichalcogenides demonstrate a range of unique and complementary optoelectronic properties. Assembling different two-dimensional materials in vertical heterostructures enables the combination of these properties in one device, thus creating multifunctional optoelectronic systems with superior(More)
1–3. It has been predicted that this edge state configuration could occur in graphene when spin-split electron-and hole-like Landau levels are forced to cross at the edge of the sample 4–6. In particular, a quantum-spin-Hall analogue has been predicted in bilayer graphene with a Landau level filling factor ν = 0 if the ground state is a spin ferromagnet 7.(More)
Exploiting the light-like properties of carriers in graphene could allow extreme non-classical forms of electronic transport to be realized 1–8. In this vein, finding ways to confine and direct electronic waves through nanoscale streams and streamlets, unimpeded by the presence of other carriers, has remained a grand challenge 9–12. Inspired by guiding of(More)