Magnetization relaxation of Mn12-Ac in the presence of crystal imperfections

Abstract Effects of crystal imperfection on the magnetic properties of Mn 12 -Ac have been studied. Crystal defects were introduced in the lattices of Mn 12 -Ac by a novel heat-treatment process. The magnetization relaxation associated with quantum tunneling of magnetization is strongly influenced by the existence of crystal defects. Experimental data are explained qualitatively in terms of the distribution of transverse anisotropy induced by the crystal imperfection.