CRYSTAL-STRUCTURE AND MAGNETIC-PROPERTIES OF [MN12O12(O2CPH)(16)(H2O)(4)].2(PHCO2H) - EVIDENCE OF DOMAIN FORMATION WITH DIFFERENT BLOCKING TEMPERATURES

We studied the crystal structures and magnetic properties of the solva ted Mn-12 benzoate cluster, [Mn12O12(O2CPh)(16)(H2O)(4)]. 2PhCO(2)H. T his crystal includes nonparallel molecular-plane orientations in the u nit cell. The single crystal magnetization curve at 1.7 K shows a hyst eresis loop that is very unusual in shape. The curve can be well under stood, assuming the following about two domains: that magnetization ro tation is frozen in one of the two and is not in the other. This two d omain model can also consistently explain the temperature dependence o f the ac susceptibility.