Interacting Boson Theory of the Magnetization Process of the Spin-1/2 Ferromagnetic-Antiferromagnetic Alternating Heisenberg Chain

TL;DR

This paper models the low temperature magnetization of a spin-1/2 ferromagnetic-antiferromagnetic Heisenberg chain using an interacting boson approximation, providing insights into its excitations and finite temperature behavior.

Contribution

It introduces a boson approximation approach to analyze the magnetization process, including finite temperature effects, and compares results with Monte Carlo simulations.

Findings

The boson approximation effectively describes low field and near saturation magnetization.

Finite temperature properties are computed via numerical solutions of integral equations.

Comparison with Monte Carlo shows good agreement within certain regimes.

Abstract

The low temperature magnetization process of the ferromagnetic-antiferromagnetic Heisenberg chain is studied using the interacting boson approximation. In the low field regime and near the saturation field, the spin wave excitations are approximated by the $\delta$ function boson gas for which the Bethe ansatz solution is available. The finite temperature properties are calculated by solving the integral equation numerically. The comparison is made with Monte Carlo calculation and the limit of the applicability of the present approximation is discussed.