Quantum Antiferromagnets in a Magnetic Field

TL;DR

This paper provides a theoretical analysis of low-dimensional quantum antiferromagnets in magnetic fields using nonlinear sigma models, revealing different magnetic regimes and applying the model to a specific compound.

Contribution

It introduces a comprehensive theoretical framework for understanding quantum antiferromagnets in magnetic fields, including a renormalization-group approach and application to real materials.

Findings

Identification of spin-gap, linear magnetization, and saturation regimes.

Application of the model to the CuHpCl compound.

Use of 1/N expansion and renormalization-group methods.

Abstract

Motivated by recent experiments on low-dimensional quantum magnets in applied magnetic fields, we present a theoretical analysis of their properties based on the nonlinear sigma model. The spin stiffness and a 1/N expansion are used to map the regimes of spin-gap behavior, predominantly linear magnetization, and spin saturation. A two-parameter renormalization-group study gives the characteristic properties over the entire parameter range. The model is relevant to many systems exhibiting Haldane physics, and is applied here to the two-chain spin ladder compound CuHpCl.