On the equivalence between magnetic-field-induced phase transitions in the integer quantum Hall effect

Magnetic-field-induced phase transitions in the two-dimensional electron system in a AlGaAs/InGaAs/GaAs heterostructure are studied. Two kinds of magnetic-field-induced phase transitions, plateau–plateau (P–P) and insulator–quantum Hall conductor (I–QH) transitions, are observed in the integer quantum Hall effect regime at high magnetic fields. In the P–P transition, both the semicircle law and the universality of critical conductivities are broken and we do not observe the universal scaling. However, the P–P transition can still be mapped to the I–QH transition by the Landau-level addition transformation, and as the temperature decreases the critical points of these two transitions appear at the same temperature. Our observations indicate that the equivalence between P–P and I–QH transitions can be found by the suitable analysis even when some expected universal properties are invalid.