Reduction of ordered moment and Neel temperature of quasi-one-dimensional antiferromagnets Sr2CuO3 and Ca2CuO3

We report elastic neutron diffraction and muon spin relaxation (mu SR) measurements of the quasi-one-dimensional antiferromagnets Sr2CuO3 and Ca2CuO3, which have extraordinarily reduced T-N/J ratios. We observe almost resolution-limited antiferromagnetic Bragg reflections in Sr2CuO3 and obtain a reduced ordered moment size of similar to 0.06 mu(B). We find that the ratio of ordered moment size mu(Ca2CuO3)/mu(Sr2CuO3) = 1.5(1) roughly scales with their Neel temperatures, which suggests that the ordered moment size of quasi-one-dimensional antiferromagnets decreases continuously in the limit of vanishing interchain interactions.