Magnetic properties and spin dynamics in magnetic molecule {Mn3}

We report dc magnetization and nuclear magnetic resonance (NMR) measurements in a trinuclear manganese compound, {Mn3}, with formula [Mn3O(O2CCH3)6(C5H5N)3]⋅C5H5N. The magnetic properties are characterized by two antiferromagnetic (AF) coupling constants, J=−7.9 K and J′=−27.6 K. 1H NMR linewidth strongly depends on both the magnetic field and temperature, and is quantitatively explained by the dipolar interaction between proton nuclei and Mn ion spins. The strong enhancement of T1−1 at low temperatures is ascribed to the slowing down of magnetic fluctuations resulting from building up of AF correlations. From the T dependence of T1−1 at low T, we obtained the gap ΔNMR=19 K, in qualitative agreement with the gap Δ≅12 K obtained from susceptibility χ.