Spin Glass Behavior in the Frustrated Antiferromagnetic LiNiO2

LiNiO2 is a member of the solid solution series LixNi2-xO2 and has been suggested as an experimental spin 12 triangular lattice antiferromagnet. It is therefore thought to be a good candidate for spin liquid behavior. We have carried out detailed structural studies using powder X-ray and neutron diffraction with Rietveld profile refinement on five different samples of LixNi2-xO2 with x near 1. The results show that there are always some nickel atoms occupying sites in the lithium layers even when x = 1. We show that the presence of nickel atoms in these sites profoundly affects the magnetic behavior and can easily explain the differences in magnetic behavior for LiNiO2 previously reported in the literature. Magnetic susceptibility data on these samples show high temperature behavior similar to previously reported results. At low temperatures spin glass freezing is observed at Tl = 9 K for samples with x ≈ l. Low-field measurements on such samples are necessary in order to see this clearly. A simple exchange model is proposed which explains most of the experimental results, thus showing that the spin liquid interpretation of previous workers is unnecessary.