Two-Dimensional Quantum Ferromagnets

TL;DR

This paper compares analytical and numerical methods to study two-dimensional quantum ferromagnets, focusing on magnetization and relaxation rates, and finds specific models work better at different temperature regimes.

Contribution

It demonstrates the effectiveness of SU(N) Schwinger boson theory at low temperatures and O(N) models at higher temperatures for quantum Hall ferromagnets.

Findings

SU(N) Schwinger boson theory accurately predicts low-temperature magnetization.

O(N) model performs well at higher temperatures.

Good agreement between analytic and numerical results.

Abstract

We present 1/N Schwinger boson and quantum Monte Carlo calculations of the magnetization and NMR relaxation rate for the two-dimensional ferromagnetic Heisenberg model representing a quantum Hall system at filling factor nu=1. Comparing the analytic and numerical calculations, we find that the SU(N) version of Schwinger boson theory gives accurate results for the magnetization at low temperatures, whereas the O(N) model works well at higher temperatures.