Magnetic Relaxation in a Single-Molecule Magnet Mn ₁₂-Chlorobutylate

Magnetization measurements have been performed on the single-molecule magnet Mn₁₂chlorobutylate, a derivative compound of the well-known Mn₁₂-acetate. A single crystal of Mn₁₂chlorobutylate has been characterized by measuring the magnetization as a function of the temperature and the magnetic field. Below the blocking temperature, magnetization curves show hysteric behavior with distinct steps at well-defined fields, indicating the quantum tunneling of magnetization in this compound. Magnetic-relaxation measurements have also been performed at various temperatures, and the effective barrier height against magnetization reversal has been determined, As compared with Mn₁₂-acetate, the relaxation rate is enhanced significantly while the effective barrier height is almost unchanged, This observation is consistent with the existence of transverse anisotropy in this compound.