Crystal defects and spin tunneling in single crystals of Mn12 clusters -: art. no. 161407

The question addressed in this paper is that of the influence of the density of dislocations on the spin tunneling in Mn-12 clusters. We have determined the variation in the mosaicity of fresh and thermally treated single crystals of Mn-12 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.