A Highly Correlated Topological Bubble Phase of Composite Fermions

TL;DR

This paper reports the experimental observation of a highly correlated topological bubble phase of composite fermions, characterized by clustering and charge order, evidenced by reentrant fractional quantum Hall effects.

Contribution

It provides the first experimental evidence of a bubble phase of composite fermions, revealing a new class of strongly correlated topological phases driven by quasiparticle clustering.

Findings

Observation of reentrant fractional quantum Hall effect.

Identification of a bubble phase with two composite fermions per bubble.

Demonstration of a new strongly correlated topological phase.

Abstract

Strong interactions and topology drive a wide variety of correlated ground states. Some of the most interesting of these ground states, such as fractional quantum Hall states and fractional Chern insulators, have fractionally charged quasiparticles. Correlations in these phases are captured by the binding of electrons and vortices into emergent particles called composite fermions. Composite fermion quasiparticles are randomly localized at high levels of disorder and may exhibit charge order when there is not too much disorder in the system. However, more complex correlations were predicted when composite fermion quasiparticles cluster into a bubble, then these bubbles order on a lattice. Such a highly correlated ground state was termed the bubble phase of composite fermions. Here we report the observation of this bubble phase of composite fermions, evidenced by the reentrance of the fractional quantum Hall effect. We associate this reentrance with a bubble phase with two composite fermion quasiparticles per bubble. Our results demonstrate the existence of a new class of strongly correlated topological phases driven by clustering and charge ordering of emergent quasiparticles.