Oliver Waldmann, Ayuk M. Ako, Hans U. Güdel and Annie K. Powell
Assessment of the Anisotropy in the Molecule Mn₁₉ with a High-Spin Ground State S = ⁸³/₂ by 35 GHz Electron Paramagnetic Resonance
Inorg. Chem. 47, 3486-3488 (2008)                 

Abstract: 35 GHz electron paramagnetic resonance experiments on a powder sample of the magnetic molecule Mn₁₉ with a high-spin ground state S = ⁸³/₂ are presented. At low temperatures, the data are well described by the simulated spectra for an isolated spin with a zero-field-splitting parameter D = 0.004 cm^–1, which is, in particular, positive. Hence, Mn₁₉ is not a single-molecule magnet; the previously observed magnetic hysteresis at ultralow temperatures is likely due to intermolecular dipolar interactions.