Spin-Parity Behavior in the Exchange-Coupled Lanthanoid-Nitroxide Molecular Magnets

4th International Conference on Advanced Materials Science and Technology

Ishida, T.^1

Department of Engineering Science, University of Electro-Communications, Chofu, Tokyo

182-8585, Japan^1

关键词: AC Magnetic susceptibility;    Coordination bonds;    Frequency dependent;    Molecular electrons;    Molecular magnetism;    Nitroxides;    Single-molecule magnet;    Spin parity;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/202/1/012001/pdf
DOI  :  10.1088/1757-899X/202/1/012001

来源: IOP

【 摘 要 】

To develop lanthanoid-based magnetic materials and relevant devices, reliable prescriptions for molecular/crystal design have long been desired. Ln3+-ion dependence on the molecular magnetism was investigated in the isomorphous series [Ln(hfac)3(2pyNO)] (Ln = Tb, Dy, Ho, Er), where 2pyNO stands for tert-butyl 2-pyridyl nitroxide as a paramagnetic ligand, and hfac for 1,1,1,5,5,5-hexafluoropentane-2,4-dionate. The slow magnetization reversal was evaluated as an indication of single-molecule magnets (SMMs) by out-of-phase ac magnetic susceptibility χ". Whereas the Tb3+(4f8) and Ho3+(4f10) derivatives exhibited frequency-dependent χ", practically null χ" was recorded for the Dy3+(4f9) and Er3+(4f11) derivatives. As for another series with Ln/radical = 1/2, [Ln(hfac)3(TEMPO)2] complexes were prepared (Ln = Tb, Dy, Ho, Er, Tm; TEMPO = 2,2,6,6-tetramethylpiperidin-1-oxyl). The Dy3+and Er3+derivatives showed appreciable χ", but the Tb3+, Ho3+, and Tm3+derivatives did not. Thus, the S = 1/2 paramagnetic ligands play a role of a spin-parity switch to regulate whether the compound behaves as an SMM. In the strongly exchange-coupled regime owing to the direct radical coordination bond, the whole molecular electron counting may provide a useful criterion to predict Kramers molecules and accordingly to explore potential SMM candidates.