Berlin 2008 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 17: Poster: Trends in Ion Beam Technology, Magnetism in Thin Films, Functional Oxides, High-k Dielectric Materials, Semiconductor Nanophotonics, Nanoengineered Thin Films, Layer Deposition Processes, Layer Growth, Layer Properties, Thin Film Characterisation, Metal and Amorphous Layers, Application of Thin Films

DS 17.7: Poster

Dienstag, 26. Februar 2008, 09:30–13:30, Poster A

X-ray absorption spectroscopy of Prussian Blue analogues thin films — •Sébastien Bonhommeau, Niko Pontius, Hermann A. Dürr, and Wolfgang Eberhardt — Berliner Elektronenspeicherring-Gesellshaft für Synchrotronstrahlung m.b.H (BESSY), Albert-Einstein-Straße 15, 12489 Berlin, Germany

Prussian Blue (PB) was described for the first time in 1704. Since then, spectacular electrochemical, magnetic and photomagnetic properties have been revealed in PB and its analogues. In particular, CoFe PB analogues may display unusual photomagnetic effects arising from a light-induced Co(III)(low spin, S=0)-CN-Fe(II)(low spin, S=0) → Co(II)(high spin, S=3/2)-CN-Fe(III)(low spin, S=1/2) electron transfer accompanied by a spin change of Co. On the other hand, MnFe PB analogues exhibit transitions between the cubic Fe(III)(low spin, S=1/2)-CN-Mn(II)(high spin, S=5/2) phase and the tetragonal Fe(II)(low spin, S=0)-CN-Mn(III)(high spin, S=2) phase due to a charge-transfer-induced Jahn-Teller distortion.

We present X-ray absorption measurements performed at BESSY on RbCoFe, NaCoFe and RbMnFe PB 200 nm-thin films deposited on top of silicon nitride membranes. The experimental spectra are analysed using simulations based on the multiplet theory to estimate the properties of these films (crystal field, charge transfer, etc) compared to powder samples as well as the number of photoexcited CoFe and MnFe pairs.