Magnetic Field Induced Insulating Phases at Large $r_s$

TL;DR

This study investigates the complex insulating phases in a low-density two-dimensional hole system under magnetic fields, revealing non-monotonic phase transitions and a shifting quantum Hall state as density varies.

Contribution

It uncovers a rich phase diagram with non-monotonic insulating phase behavior and a transition of the quantum Hall state at low densities, expanding understanding of strongly correlated 2D systems.

Findings

Reentrant insulating phase initially strengthens then weakens with decreasing density.

At lowest densities, the quantum Hall state shifts from ν=1/3 to ν=1.

The phase behavior can be explained by a non-monotonic melting line in phase space.

Abstract

Exploring a backgated low density two-dimensional hole sample in the large $r_s$ regime we found a surprisingly rich phase diagram. At the highest densities, beside the $\nu=1/3$, 2/3, and 2/5 fractional quantum Hall states, we observe both of the previously reported high field insulating and reentrant insulating phases. As the density is lowered, the reentrant insulating phase initially strengthens, then it unexpectedly starts weakening until it completely dissapears. At the lowest densities the terminal quantum Hall state moves from $\nu=1/3$ to $\nu=1$. The intricate behavior of the insulating phases can be explained by a non-monotonic melting line in the $\nu$-$r_s$ phase space.