Impurity Induced Antiferromagnetism in Spin-1/2 HeisenbergTwo-Leg Ladder Systems

Abstract

Based on the phase Hamiltonian representation of a spin-1/2 Heisenberg two-leg ladder system coupled antiferromagnetically, which has a spin gap if clean, it is shown that a non-magnetic impurityreplacing a spin inducesa staggered spin modulation.This results in the long range order of antiferromagnetismin the presence of three-dimensional coupling between the ladders.This will be in accordance with a recent experimental observation byAzuma et al. on Sr(Cu_1-xZn_x)_2O_3.