Ground State and Magnetization Process of the Mixture of Bond-Alternating and Uniform S=1/2 Antiferromagnetic Heisenberg Chains

TL;DR

This study uses the density matrix renormalization group method to analyze the ground state and magnetization of mixed bond-alternating and uniform S=1/2 antiferromagnetic Heisenberg chains, fitting experimental data.

Contribution

It introduces a detailed numerical analysis of mixed chains and clarifies the effects of bond-alternation patterns on magnetic properties, aligning with experimental observations.

Findings

Magnetization curve fits experimental data well

Low field magnetization sensitive to bond-alternation pattern

Results support the random parity model for the system

Abstract

The mixture of bond-alternating and uniform S=1/2 antiferromagnetic Heisenberg chains is investigated by the density matrix renormalization group method. The ground state magnetization curve is calculated and the exchange parameters are determined by fitting to the experimentally measured magnetization curve of \CuCl$_{2x}$Br$_{2(1-x)}$($\gamma$-pic)$_2$. The low field behavior of the magnetization curve and low temperature behavior of the magnetic susceptibility are found to be sensitive to whether the bond-alternation pattern (parity) is fixed all over the sample or randomly distributed. The both quantities are compatible with the numerical results for the random parity model.