μSR study of [Mn12O12(O2CC6H5)16(H2O)4]·2C6H5CO2H

The crystals of a Mn12 cluster, [Mn12O12(O2CC6H5)16(H2O)4]·2C6H5CO2H, are mosaic involving two kinds of molecules with different relaxation rates. The ratios of the two components in the crystals are strongly batch-dependent. We prepared a batch of crystals in which mainly contained the fast relaxation (FR) species and studied the muon spin relaxation (μSR) measurements in the range 0.3–80 K at zero-field (ZF). As the temperature was lowered, the decay of the muon asymmetry showed systematic temperature dependence: the dynamic and the static behavior of the internal-field appear alternately. This is probably due to the magnetization blocking of the FR molecule.