Regensburg 2010 – wissenschaftliches Programm

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KR: Fachverband Kristallographie

KR 10: Poster: Multiferroics (with MA, DF, KR, DS)

KR 10.4: Poster

Dienstag, 23. März 2010, 10:45–13:45, Poster A

Incoherent Slow Magnetisation Dynamics in the Giant Keplerat Molecule Fe₃₀Mo₇₂ — •T. Dellmann¹, H.-H. Klauss¹, J. Schnack², and B. Büchner³ — ¹Institut für Festkörperphysik, TU Dresden — ²Fakultät für Physik, Univ. Bielefeld — ³Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden

In the geometrically frustrated polyoxomolybdate nanomolecule Fe₃₀Mo₇₂ a distinct slowing down of the magnetisation dynamics is observed at temperatures of about 5K depending on the observation method [1, 2]. These dynamics still persist at very low temperatures down to 20 mK as shown by local probe techniques. Furthermore, no magnetisation steps could be found in the field dependent magnetisation at these temperatures as predicted by the quantum rotational band model [3].

We present recent low temperature ac-susceptibility results for different frequencies (200 Hz < f < 10 kHz) and external fields (0 < B < 2 T) and discuss them in comparison with results from µ⁺SR, NMR and ⁵⁷Fe moessbauer spectroscopy. The orign of decoherence at lowest temperatures is focussed in this discussion.

[1] Chr. Schröder et al., Phys.Rev.B 77, 224409 (2008)

[2] J. Lago et al., Phys.Rev.B 76, 064432 (2007)

[3] J. Schnack et al., Europhys. Lett., 56 (6), pp. 863-869 (2001)