Crystal structure and magnetic properties of [${\mathrm{Mn}}_{12}{\mathrm{O}}_{12}{(\mathrm{O}}_2{\mathrm{C}\mathrm{P}\mathrm{h})}_{16}{(\mathrm{H}}_2{\mathrm{O})}_4{\left]\mathrm{\cdot }2\right(\mathrm{P}\mathrm{h}\mathrm{C}\mathrm{O}}_2\mathrm{H}):$ Evidence of domain formation with different blocking temperatures

We studied the crystal structures and magnetic properties of the solvated Mn${}_{12}$ benzoate cluster, [Mn${}_{12}$O${}_{12}$(O${}_2$CPh)${}_{16}$(H${}_2$O)${}_4$]$\cdot$2PhCO${}_2$H. This crystal includes nonparallel molecular-plane orientations in the unit cell. The single crystal magnetization curve at 1.7 K shows a hysteresis loop that is very unusual in shape. The curve can be well understood, assuming the following about two domains: that magnetization rotation is frozen in one of the two and is not in the other. This two domain model can also consistently explain the temperature dependence of the ac susceptibility.