Antiferromagnetic spin structure in BaCoO3BaCoO3 below 15 K determined by neutron and μ+SRμ+SR

The magnetic structure of the antiferromagnetic (AF) hexagonal perovskite BaCoO3BaCoO3 was investigated by means of neutron powder diffraction in the temperature range between 60 and 1.5 K. AF diffraction peaks appear below the Néel temperature (TN=15K). Although several possible spin arrangements fit the neutron diffraction pattern, when combined with the results of a muon spin spectroscopy experiment, the most reasonable description of the AF state in BaCoO3BaCoO3 is a modulated structure along the (110) direction, described as ml=m0cos(2πkl), where mlml is the moment at the Co4+Co4+ site ll, m0=(0,0,0.53μB) at 1.5 K and kk is the propagation vector (13,13,0).