Inelastic neutron scattering studies on the 3d-4f heterometallic single-molecule magnet Mn2Nd2

The discovery of slow relaxation and quantum tunneling of the magnetization in Mn12ac more than 15 years ago has inspired both physicists and chemists alike. This class of molecules, now called single-molecule magnets (SMMs), has very recently been expanded to heterometallic clusters incorporating transition metal and rare earth ions. The 4f ions were chosen because of their large angular momentum and magnetic anisotropy. Inelastic neutron scattering experiments were performed on the time-of-flight disk-chopper spectrometer IN5 at ILL on the SMM Mn2Nd2. A magnetic model was developed which perfectly describes all data, including the magnetic data. It was found that neither the large anisotropy nor the large angular momentum of the NdIII ions is the main reason for the SMM behavior in this molecule. Our analysis of the data indicates that it is the weak coupling of the NdIII ions to the MnIII ions, usually considered as a drawback of rare earth ions, which enhances the relaxation time and therefore leads to SMM behavior.