Anomalously large resistance at the charge neutrality point in a zero-gap InAs/GaSb bilayer

Magnetoresistance measurements of graphene at the charge neutrality point.

We report on transport measurements of the insulating state that forms at the charge neutrality point of graphene in a magnetic field. Using both conventional two-terminal measurements, sensitive to bulk and edge conductance, and Corbino measurements, sensitive only to the bulk conductance, we observed a vanishing conductance with increasing magnetic fields. By examining the resistance changes ...

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Evidence for a spin phase transition at charge neutrality in bilayer graphene

The quantum spin Hall effect is characterized by spin-polarized counter-propagating edge states1–3. It has been predicted that this edge state configuration could occur in graphene when spin-split electronand hole-like Landau levels are forced to cross at the edge of the sample4–6. In particular, a quantumspin-Hall analogue has been predicted in bilayer graphene with a Landau level filling fact...

Giant magnetodrag in graphene at charge neutrality.

We report experimental data and theoretical analysis of Coulomb drag between two closely positioned graphene monolayers in a weak magnetic field. Close enough to the neutrality point, the coexistence of electrons and holes in each layer leads to a dramatic increase of the drag resistivity. Away from charge neutrality, we observe nonzero Hall drag. The observed phenomena are explained by decoupl...

Microwave zero-resistance states in a bilayer electron system.

Magnetotransport measurements on a high-mobility electron bilayer system formed in a wide GaAs quantum well reveal vanishing dissipative resistance under continuous microwave irradiation. Profound zero-resistance states (ZRS) appear even in the presence of additional intersubband scattering of electrons. We study the dependence of photoresistance on frequency, microwave power, and temperature. ...