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تسجيل مستخدم جديدForbidden transitions between quantum Hall and insulating phases in p-SiGe heterostructures
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We show that in dilute metallic p-SiGe heterostructures, magnetic field can cause multiple quantum Hall-insulator-quantum Hall transitions. The insulating states are observed between quantum Hall states with filling factors u=1 and 2 and, for the first time, between u=2 and 3 and between u=4 and 6. The latter are in contradiction with the original global phase diagram for the quantum Hall effect. We suggest that the application of a (perpendicular) magnetic field induces insulating behavior in metallic p-SiGe heterostructures in the same way as in Si MOSFETs. This insulator is then in competition with, and interrupted by, integer quantum Hall states leading to the multiple re-entrant transitions. The phase diagram which accounts for these transition is similar to that previously obtained in Si MOSFETs thus confirming its universal character.
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