Dresden 2003 – wissenschaftliches Programm

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MA: Magnetismus

MA 23: Bio-und molekularer Magnetismus

MA 23.10: Vortrag

Donnerstag, 27. März 2003, 12:30–12:45, HSZ/401

Magnetic interactions and chemical bonding in No-dqferric wheelNo-dq — •A. V. Postnikov, S. G. Chiuzbăian, and M. Neumann — Universität Osnabrück – Fachbereich Physik, 49069 Osnabrück

Electronic structure of the No-dqferric wheelNo-dq { Li⊂Fe₆[N(CH₂CH₂O)₃]₆ } Cl molecule [1] has been studied from first principles by the siesta method [2], based on density functional theory and numerical basis orbitals, using both local density (LDA) and generalized gradient (GGA) approximations. Local moments on Fe sites persist in ferromagnetic (FM), different antiferromagnetic (AFM) and ferrimagnetic trial configurations, maintaining their magnitude of nearly 4 µ_B. GGA favours higher localization of magnetic moments on the Fe sites, but does not increase the net magnetic moment of the FM molecule over the LDA result. The lowest energy configuration is AFM; interatomic exchange parameters are extracted from total energy differences and compared with experimental estimates due to neutron scattering [3]. The complete saturation of the Fe magnetic moment is prevented by a substantial Fe–O hybridisation. Experimental studies of the occupied density of states have been performed by means of X-ray photoelectron spectroscopy and soft X-ray emission spectroscopy.

[1] R. W. Saalfrank, I. Bernt el al., Angew. Chem. 109 (1997) 2596.

[2] J. M. Soler et al., J. Phys. Cond. Matter 14 (2002) 2745.

[3] O. Waldmann el al., Inorg. Chem. 38 (1999) 5879.