Dielectric and magnetic relaxations of the quantum nanomagnet Mn-12-acetate

The temperature dependent dielectric and magnetic relaxations in the quantu m nanomagnet Mn-12-Acetate and its partially and fully deuterated analogs h ave been studied. One magnetic mode and four dielectric modes have been ide ntified in the temperature interval from 300 K to 2.8 K and in the frequenc y range from 20 Hz to 1 MHz. The relaxation times of all modes follow an Ar rhenius law. Comparison of the magnetic susceptibility mode to the NMR data shows that the magnetic susceptibility mode can be related to the magnetiz ation reorientation fluctuations, while three slowest dielectric modes can be attributed to the motion of H2O and the forth mode to that of the CH3 gr oups.