Crystal defects and spin tunneling in single crystals of Mn₁₂ clusters

The question addressed in this paper is that of the influence of the density of dislocations on the spin tunneling in Mn₁₂ clusters. We have determined the variation in the mosaicity of fresh and thermally treated single crystals of Mn₁₂ by analyzing the widening of low angle x-ray diffraction peaks. It has also been well established from both isothermal magnetization and relaxation experiments that there is a broad distribution of tunneling rates which is shifted to higher rates when the density of dislocations increases.