Chain breaks and the susceptibility of Sr_2Cu_{1-x}Pd_xO_{3+\delta} and other doped quasi one-dimensional antiferromagnets

TL;DR

This paper investigates how chain breaks caused by non-magnetic impurities affect the magnetic susceptibility of quasi-one-dimensional antiferromagnets, providing analytical results and explaining experimental observations.

Contribution

It derives a parameter-free analytical expression for susceptibility of finite chain segments and applies it to interpret experimental data on Sr_2Cu_{1-x}Pd_xO_{3+\delta}.

Findings

Analytical susceptibility results match Quantum-Monte-Carlo simulations.

Chain segmentation explains Curie-like susceptibility in experiments.

Additional impurities have minor effects on susceptibility.

Abstract

We study the magnetic susceptibility of one-dimensional S=1/2 antiferromagnets containing non-magnetic impurities which cut the chain into finite segments. For the susceptibility of long anisotropic Heisenberg chain-segments with open boundaries we derive a parameter-free result at low temperatures using field theory methods and the Bethe Ansatz. The analytical result is verified by comparing with Quantum-Monte-Carlo calculations. We then show that the partitioning of the chain into finite segments can explain the Curie-like contribution observed in recent experiments on Sr_2Cu_{1-x}Pd_xO_{3+\delta}. Possible additional paramagnetic impurities seem to play only a minor role.