Evidence for Skyrmion crystallization from NMR relaxation experiments

TL;DR

This study uses NMR relaxation experiments to provide evidence that the magnetic ground state near complete filling of the first Landau level in a 2D electron gas forms a Skyrmion crystal, revealing a new topological spin texture.

Contribution

First experimental evidence linking nuclear spin relaxation to Skyrmion crystallization in a quantum Hall system.

Findings

Nuclear spin relaxation rate increases near quantum Hall states.

Strong correlation between relaxation and electron localization.

Indications of a Skyrmion lattice in the ground state.

Abstract

A resistively detected NMR technique was used to probe the two-dimensional electron gas in a GaAs/AlGaAs quantum well. The spin-lattice relaxation rate $(1/T_{1})$ was extracted at near complete filling of the first Landau level by electrons. The nuclear spin of $^{75}$As is found to relax much more efficiently with $T\to 0$ and when a well developed quantum Hall state with $R_{xx}\simeq 0$ occurs. The data show a remarkable correlation between the nuclear spin relaxation and localization. This suggests that the magnetic ground state near complete filling of the first Landau level may contain a lattice of topological spin texture, i.e. a Skyrmion crystal.