Orbitally tuned composite-fermion metal-to-superfluid transitions

TL;DR

This paper demonstrates a controllable transition between metallic and superfluid phases of composite fermions in bilayer graphene, revealing non-Abelian states and orbital-dependent pairing mechanisms through experimental and numerical analysis.

Contribution

It introduces a method to induce and study composite-fermion pairing transitions via orbital control in bilayer graphene, highlighting the orbital origin of non-Abelian quantum Hall states.

Findings

Transport measurements show a transition from conductive states to quantized plateaus.

States are insensitive to in-plane magnetic fields, indicating single-component ground states.

Numerical models support the orbital origin of the pairing transition and suggest non-Abelian Moore-Read or anti-Pfaffian states.

Abstract

The effective interaction between composite fermions, set entirely by the Coulomb potential and the underlying electronic Landau level orbitals, can stabilize exotic fractional quantum Hall states. In particular, half-filled Landau levels with different orbital character can host either metallic or paired phases of composite fermions. Here, we leverage experimental control over the orbital composition to realize a composite-fermion pairing transition in the first excited Landau level of bilayer graphene. Transport measurements at filling factors v = 9/2 and 11/2 reveal conductive states giving way to well-developed plateaus with increasing displacement fields. These states are insensitive to an in-plane magnetic field, indicating single-component ground states and thus pointing at non-Abelian orders. Our numerical study, based on displacement-field-dependent Landau-level wavefunctions, supports the orbital origin of the pairing transition and suggests Moore-Read or anti-Pfaffian ground states.