Berlin 2008 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 13: Growth

MM 13.5: Vortrag

Montag, 25. Februar 2008, 15:45–16:00, H 0111

Optical-image-furnace growth and characterisation of transition metal Heusler compounds — •Andreas Neubauer, Christian Franz, and Christian Pfleiderer — Physik-Department E21, Technische Universität München, D-85747 Garching, Germany

Both full (X₂YZ) and half (XYZ) Heusler compounds offer a huge variety of electronic and magnetic phenomena [1], e.g., half-metallic ferromagnetism, the magnetic shape memory effect, heavy-fermion behavior and unusual antiferromagnetic states. To gain further information about the physical properties of Heusler compounds detailed studies on high quality single crystals are essential. In recent years it has been found that optical as opposed to RF heated floating zone crystal growth produces very high quality single crystals [2]. Minimizing sample contamination (e.g. oxygen) is thereby a key prerequisite for high quality crystals. Going beyond present day technology [2], we set up a commercial image furnace for use with ultra-high vacuum and ultra-pure inert gas atmosphere by converting it to all metal-sealing. The furnace may be baked out to reduce any residual contamination by the system. To prepare polycrystalline feed rods for single-crystal growth we also set up a RF heated high-purity casting assembly employing a Hukin-type cold-crucible. Single crystals of the Heusler compounds Mn₃Si and Fe₂TiSn were grown and characterised. We present a structural analysis as well as transport and thermodynamic bulk properties. [1] for a review see e.g., I. Galanakis et al, cond-mat/0709.4183v2 (2007). [2] G. Behr, W. Löser, Recent Res. Devel. Crystal Growth 4, 129 (2005).