The effect of the density of dislocations upon spin tunneling in Mn12 clusters was studied. The variation in the mosaicity of fresh and thermally treated single crystals of Mn12 was determined by analyzing the widening of low-angle X-ray diffraction peaks. It was also

well established, by isothermal magnetization and relaxation experiments, that there was a broad distribution of tunneling rates which shifted to higher rates when the density of dislocations increased.

Crystal Defects and Spin Tunnelling in Single Crystals of Mn12 Clusters. J.M.Hernandez F.Torres, J.Tejada, E.Molins: Physical Review B, 2002, 66[16], 161407 (4pp)