Unconventional fractional quantum Hall states and Wigner crystallization in suspended Corbino graphene

TL;DR

This study explores the competition between Wigner crystallization and unconventional fractional quantum Hall states in suspended graphene, revealing new phases and transitions driven by electron interactions in a Corbino device geometry.

Contribution

It uncovers unconventional FQH states not fitting standard models and demonstrates Wigner crystallization at very low charge densities in graphene, advancing understanding of electron ordered phases.

Findings

Unconventional FQH states originate from residual composite fermion interactions.

Electrons form a Wigner solid at very low densities, transitioning to a Hall liquid.

Charge density modulates electron transport and phase behavior.

Abstract

Competition between liquid and solid states in two-dimensional electron system is an intriguing problem in condensed matter physics. We have investigated competing Wigner crystal and fractional quantum Hall ( FQH ) liquid phases in atomically thin suspended graphene devices in Corbino geometry. Low temperature magnetoconductance and transconductance measurements along with $IV$ characteristics all indicate strong charge density dependent modulation of electron transport. Our results show unconventional FQH phases which do not fit the standard Jain's series for conventional FQH states, instead they appear to originate from residual interactions of composite fermions in partially filled higher Landau levels. And at very low charge density with filling factors $\nu \lesssim$ 1/5, electrons crystallize into an ordered Wigner solid which eventually transforms into an incompressible Hall liquid at filling factors around $\nu \leq$ 1/7. Building on the unique sample structure, our experiments pave the way for enhanced understanding of the ordered phases of interacting electrons.