NMR Tracing of Hyperfine-Mediated Nuclear Spin Diffusion in Fractional Quantum Hall Domain Phases

TL;DR

This study demonstrates enhanced nuclear spin diffusion in fractional quantum Hall domain phases, revealing hyperfine-mediated interactions that cause rapid polarization spreading across the material.

Contribution

The paper introduces a novel NMR technique to probe hyperfine-mediated nuclear spin diffusion in fractional quantum Hall phases, highlighting the role of domain-wall dynamics.

Findings

Nuclear spin polarization spreads beyond pinning centers.

Enhanced diffusion linked to hyperfine interactions.

Resistively-detected NMR reveals domain-related polarization behavior.

Abstract

We present an enhanced diffusion of nuclear spin polarization in fractional quantum Hall domain phases at $\nu = 2/3$. Resistively-detected NMR mediated by electrically driven domain-wall motion is used as a probe of local nuclear polarization, manifesting pumping-dependent signal saturation behavior. This reveals that a relatively homogeneous polarization profile spreads even to places distant from pinning centers of the domain walls. We attribute this to the fact that the pumped nuclear polarization near the domain walls rapidly diffuses into the domains where nuclei experience Knight fields on comparable levels. The anomalous enhancement of nuclear diffusion may be interpreted in terms of indirect hyperfine-mediated interaction between nuclear spins in the domains.