New universality at the magnetic field driven insulator to integer quantum Hall effect transitions

초록

We present a magnetotransport study of a disordered two-dimensional hole system in a strained Ce quantum well. As the magnetic field is increased, a clear transition from a low magnetic field insulator to the nu = 1 quantum Hall state at the lowest density range (controlled by a gate), and to the nu = 3 state at higher densities, is observed. We find that these transitions are characterized by a new universality: At the critical point, the diagonal and Hall resistivities are equal, within experimental uncertainty. These results are in conflict with the ''floating'' scenario suggested by Khmel'nitzkii [JETP Lett. 38, 552 (1983)] and Laughlin [Phys. Rev. Lett. 52, 2304 (1984)].

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