Short-range magnetic correlations in spinel LiMn2O4

Neutron diffraction, inelastic neutron scattering, and ac magnetic susceptibility measurements were performed to study the magnetic correlations of the Mn spins in a fully oxygenated lithium manganospinel Li0.96Mn2O4. The compound crystallizes into a cubic structure of the Fd3̄m symmetry at 300 K and an orthorhombic Fddd symmetry at 150 K. Two separate types of magnetic phase transitions were found, signifying that the Mn3+ and Mn4+ spins order separately at two different temperatures. The magnetic correlations were antiferromagnetic in nature, and were observed to develop below 80 and 55 K, respectively, for the two components. Surprisingly, for both components the correlation lengths reached their maxima at 45 and 30 K, but were still short-range with correlation lengths at ∼120 and ∼40 Å, respectively.