Reduced size of ordered moments of a quasi 1d antiferromagnet Sr2CuO3

The quasi one-dimensional antiferromagnet Sr2CuO3 exhibits Neel order of Cu2+ moments (S=1/2) at T-N = 5.41(1) K, as demonstrated by (1) almost resolution-limited magnetic Bragg reflections in neutron scattering measurements, and (2) spontaneous muon spin precession in zero-field muon spin relaxation (mu SR) measurements. The temperature dependence of the order parameters are consistent between the two experimental techniques. From the neutron data, we obtained an upper-limit for the ordered moment size of similar to 0.06 mu(B). This indicates a significant moment reduction from quantum fluctuations.