Skyrmion Liquid Phase of the Quantum Ferromagnet in Two Dimensions

TL;DR

This paper theoretically investigates a skyrmion liquid phase in a two-dimensional quantum ferromagnet near the quantum Hall filling factor, revealing a crossover between ferromagnetic and paramagnetic phases and identifying a new collective cyclotron mode.

Contribution

It introduces the concept of a skyrmion liquid phase in 2D quantum ferromagnets and characterizes its properties near the quantum Hall filling factor.

Findings

Identifies a crossover between ferromagnetic and paramagnetic phases near ν=1.

Discovers a new collective cyclotron mode in the skyrmion liquid.

Findings align with recent Knight-shift measurements.

Abstract

The two-dimensional quantum ferromagnet filled with a liquid of skyrmions is studied theoretically in the context of the quantum Hall effect near electronic filling factor $\nu = 1$. A cross-over between the classical ferromagnetic phase at $\nu =1$ and a classical paramagnetic phase at $\nu \neq 1$ is obtained, which is consistent with recent Knight-shift measurements. A new collective mode associated with the skyrmion liquid that is of the cyclotron type is also identified.