Complete spin phase diagram of the fractional quantum Hall liquid

TL;DR

This paper introduces a new spin-resolved pulsed tunneling technique to accurately map the ground-state spin-polarization phase diagram in quantum Hall systems, revealing fully-polarized states at low magnetic fields and challenging existing models.

Contribution

The study presents a novel SRPT method for precise phase diagram mapping, providing new insights into spin states in quantum Hall systems beyond previous techniques.

Findings

Identification of fully-polarized states at low magnetic fields

Deviation from the composite-fermion model in certain regimes

Establishment of SRPT as a powerful investigative tool

Abstract

Study of the ground-state electronic spin-polarization can permit discovery and identification of novel correlated phases in the quantum Hall (QH) system. It can thus determine the potential usefulness of QH states for quantum computing. However, prior measurements involving optical and NMR techniques may perturb the system away from delicate ground-states. Here, we present spin-resolved pulsed tunneling (SRPT) that precisely determines the complete phase diagram of the ground-state spin-polarization as a function of magnetic field (B) and filling factor ({\nu}). We observe fully-polarized {\nu} = 5/2 and 8/3 states at very small B, suggesting strong deviation from the weakly-interacting composite-fermion model that largely successfully describes our phase diagram for the lowest Landau level. The results establish SRPT as a powerful technique for investigating correlated electron phenomena.