Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 10: Magnetic Materials

MA 10.13: Vortrag

Montag, 25. Februar 2008, 18:15–18:30, H 1028

Magnetism of the high spin molecules [Mn₄L₆](BF₄)₂·2CH₃-CN·H₂O and [Cr^IIIMn₃^II(PyA)₆Cl₃] — •Manuel Prinz¹, Michael Raekers¹, Karsten Kuepper², Phalguni Chaudhuri³, Simon J. George⁴, and Manfred Neumann¹ — ¹Universität Osnabrück, Fachbereich Physik, Barbarastr. 7, D-49069 Osnabrück — ²FZ Dresden-Rossendorf, Dresden, Germany — ³MPI, Mülheim an der Ruhr, Germany — ⁴LBNL, Berkeley, CA, USA

We have studied the electronic and magnetic structure of high spin molecules by spectroscopic investigations in combination with theoretical calculations. We present results on [Mn₄^IIL₆](BF₄)₂·2CH₃CN·H₂O (Mn₄)and the hetero nuclear, spin frustrated molecule [Cr^IIIMn₃^II(PyA)₆Cl₃] (CrMn₃), which have been studied using X-ray photoelectron spectroscopy (XPS), X-ray absorption and emission spectroscopy (XAS, XES), and X-ray magnetic circular dichroism (XMCD). Magnetic measurements of Mn₄ show a magnetization saturation of about 20 µ_B/f.u. at a magnetic field of B=7 T and a temperature of T=2 K. From XMCD measurements of Mn₄ at T=5 K and B=5 T we obtained a high magnetic moment of 18.5 µ_B/f.u, whereas a quenching of the Mn orbital moments was observed (m_orb=0.4 µ_B/f.u.). The element selective Mn^II and Cr^III dichroic signals of the CrMn₃ complex at B=5 T and T=5 K where recorded. For the three Mn^II ions a magnetic moment of ≈ 15 µ_B was determined. For both complexes we will present a comparison to XAS/XMCD charge transfer multiplet calculations.