Regensburg 2010 – scientific programme

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MA: Fachverband Magnetismus

MA 2: Bio- and Molecular Magnetism

MA 2.7: Talk

Monday, March 22, 2010, 12:15–12:30, H10

High-field ESR on the Mn₂Ni₃ single molecular magnet — •Y. Krupskaya¹, A. Das², K. Gieb³, W. Kroener³, S. Demeshko², S. Dechert², R. Klingeler¹, V. Kataev¹, P. Müller³, F. Meyer², and B. Büchner¹ — ¹Leibniz Institute for Solid State and Materials Research (IFW) Dresden, D-01171 Dresden, Germany — ²Institut für Anorganische Chemie, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany — ³Lehrstuhl für Experimentalphysik, Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany

Magnetic properties of a novel metal-organic molecular complex with [Mn(III)₂Ni(II)₃(µ-O)₈] core have been studied by means of high-field electron spin resonance (HF-ESR) spectroscopy and magnetization measurements. We observe a ferromagnetic coupling between three Ni(II) and two Mn(III) ions which yields a high spin magnetic ground state with S_tot=7. Frequency-tunable HF-ESR spectroscopy reveals a substantial magnetic anisotropy gap with a negative axial anisotropy D=−0.55 K which gives evidence for a bistable (easy axis) magnetic ground state of the molecule. The analysis of the ESR data by means of a minimal effective spin Hamiltonian enables an accurate description of the energy level scheme and the spin states of the complex. The observed high spin ground state and the negative axial anisotropy ensure necessary prerequisites for the realization of a single molecular magnet. Indeed, at low temperatures (T<1 K) magnetization measurements reveal a single molecular magnet behavior such as hysteresis and tunnelling of the magnetization.