Dresden 2003 – wissenschaftliches Programm

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MA: Magnetismus

MA 14: Poster: Schichten(1-31), Spinabh.Trsp.(32-47), Exch.Bias(48-54), Spindyn.(55-64), Mikromag.(65-76), Partikel(77-88), Oflmag.(89-92), Spinelektr.(93-98), Elektr.Theo.(99-103), Mikromag+PhasÜ+Aniso.(104-122), MagnMat.(123-134), Messm+Mol-Mag.(135-139), Kondo(140-151)

MA 14.133: Poster

Dienstag, 25. März 2003, 15:15–19:15, Zelt

Magnetic field controlled floating-zone single crystal growth — •Hermann Regina¹, Behr Guenther ¹, Gerbeth Gunter², Priede Janis², and Schultz Ludwig¹ — ¹Leibniz Institute for Solid State and Materials Research (IFW) Dresden — ²Forschungszentrum Rossendorf e.V., Dresden

For the growth of high precision single crystals of complicated intermetallic compounds, the controlled adjustment of a solid-liquid-interface of desired curvature and the knowledge of the melt convection are of considerable importance. Numerical simulation calculations for the determination of the electromagnetic field configuration induced by the RF heater coil and the solution of the coupled heat and hydrodynamic equations were done for the model substance Ni. The significant influence of the electromagnetically driven flow, which acts opposite to the Marangoni convection, makes the solid-liquid interface concave towards the melt. Moreover, comprehensive investigations of the influence of growth parameters such as zone length, power influence and heated region on the solid-liquid interface geometry during RF floating zone crystal growth were carried out experimentally. It could be shown that undesired concave (towards the melt) interface regions cannot be avoided even at optimised parameter configurations. Therefore, the adjustment of a complete convex solid-liquid interface shape in RF-floating zone crystal growth was tackled with additional melt stirring by magnetic forces. A novel magnetic two-phase stirrer system has been applied to the floating-zone single crystal growth facility resulting in a definite improvement of the solid-liquid-interface.