Field Dependence of the Magnetization for the spin-ladder material Cu_2(C_5H_{12}N_2)_2Cl_4

TL;DR

This paper introduces a novel series expansion method to calculate the magnetization of Heisenberg spin-ladder systems under an applied field, successfully matching experimental data for the material Cu_2(C_5H_{12}N_2)_2Cl_4.

Contribution

A new series expansion technique for uniform magnetization in Heisenberg systems with field applied perpendicular to anisotropy, applicable to spin-ladder materials.

Findings

Method accurately predicts magnetization curves.

Results agree well with experimental data.

High-temperature susceptibility calculations match experiments.

Abstract

We have developed a series expansion method for calculating the uniform magnetization, M, as a function of the applied field h for Heisenberg systems at T=0. The method involves introducing Ising anisotropy along the z-axis together with an applied uniform field along the x-axis. On extrapolation to the isotropic limit, one recovers the magnetization for the Heisenberg system with an applied field along the x-axis. This method circumvents the difficulties in developing perturbation theory associated with the commuting nature of the uniform field. The results developed for two-chain ladders appropriate for the material Cu_2(C_5H_{12}N_2)_2Cl_4 are in good agreement with the experimental data. In addition, uniform susceptibility is calculated by high temperature expansions and also compared with the experimental data.