Berlin 2012 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 3: Bio- and Molecular Magnetism

MA 3.11: Vortrag

Montag, 26. März 2012, 12:15–12:30, EB 202

Different magnetization blocking mechanisms in 3d4f heterometallic single-molecular magnets; an experimental study — •Alexander Sundt¹, K. C. Modal², Y. Lan², C. E. Anson², L. Ungur³, A. K. Powell², L. Chibotaru³, and Oliver Waldmann¹ — ¹Physikalisches Institut, Universität Freiburg — ²Institute of Inorganic Chemistry, Karlsruhe Institute of Technologie — ³Devision of Quantum and Physical Chemistry and INPAC, Katholieke Universiteit Leuven

The observation of slow relaxation and quantum tunneling of the magnetization at very low temperatures in the molecule Mn₁₂ in 1993 opened the research field of single molecular magnets (SMM). Recently heterometallic SMMs of transition metal and rare earth ions have been a focus of research as the single-ion anisotropy and the large angular momentum of the rare earth ions is believed to positively contribute to the energy barrier U_eff for magnetization reversal. Relaxation studies reveal the presence of unexpected additional thermal relaxation process in these clusters.

In this talk we present magnetic studies on heterometallic clusters containing Dy^III, a highly anisotropic rare earth ion. DC magnetization, AC susceptibility, and magnetization relaxation data are recorded on e.g. the cluster Co₂Dy₂ for different temperatures, fields and AC frequencies. The experimental data show a crossover of the blocking mechanism for magnetization reversal with temperature. Our careful analysis allows us to determine them as an exchange- and a single-ion-based relaxation mechanism. Further systems will also be discussed.