Berlin 2015 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 16: Bio- and Molecular magnetism
MA 16.2: Vortrag
Dienstag, 17. März 2015, 09:45–10:00, EB 202
High-field ESR study of a new ferrous cubane SMM — •Azar Aliabadi1, Felix J Klinke2, Serhiy Demeshko2, Vladislav Kataev1, Franc Meyer2, and Bernd Büchner1 — 1IFW Dresden, Dresden, Germany — 2Institute of Inorganic Chemistry, Georg-August-University, Göttingen, Germany
Magnetic properties of a cube-like tetranuclear complex with a Fe4O4 core have been investigated by means of the high-field high-frequency tunable electron spin resonance (HF-ESR). Four Fe(II) spins S = 2 in the complex are coupled ferromagnetically yielding a high-spin ground state with Stotal = 8. The ESR spectra consist of a single line in a frequency range ≤ 332 GHz, whereas at higher frequencies a low magnetic field line appears at 4 K. The second line at the low magnetic field arises with increasing temperature. A transfer of the spectral weight to higher magnetic field at high temperatures gives evidence for an easy axis magnetic anisotropy for the entire cube. Simulated powder averaged ESR spectra for the case of the collinear alignment of four Fe(II) spins with an easy axis magnetic anisotropy agrees well with the experimental data. The calculated energy levels scheme of this system suggests a spin doublet ground state |8, ± 8> which confirms the negative sign of the axial magnetic anisotropy parameter D.
The observation of a high spin ground state with the easy axis magnetic anisotropy for the Fe4O4 -cube suggests a single-molecule magnet (SMM) behavior of the studied complex.