Reentrant insulating phases in the integer quantum Hall regime

Quantum Hall measurements are performed in a dilute high-quality GaAs two-dimensional hole system with carrier densities of (4.4-5.3)×1010cm-2. With the rs value approximately 20, the interaction effect is already strong even in the absence of magnetic field. In the integer quantum Hall regime up to 2 T, a series of reentrant insulating phases (RIPs) are observed between fillings 1, 2, 3, and 4, with peak locations periodic in 1/B. Moreover, the RIP peaks are also characterized by a striking inductance in response to ac excitations, which is likely due to the onset of a Wigner crystal state. The multiple RIP peaks indicate a more complex phase diagram than previously perceived.