Regensburg 2007 – scientific programme

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MA: Fachverband Magnetismus

MA 2: Magnetic Particles/Clusters I

MA 2.5: Talk

Monday, March 26, 2007, 11:15–11:30, H10

The origin of ferromagnetism in ⁵⁷Fe ion-implanted Silicon Carbide — •Frank Stromberg¹, Werner Keune¹, Heiko Wende¹, and Helfried Reuther² — ¹Fachbereich Physik, Universität Duisburg-Essen, Lotharstrasse 65, D-47048 Duisburg, Germany — ²Institut für Ionenstrahlphysik, Forschungszentrum Rossendorf, Bautzner Landstrasse 128, D-01328 Dresden, Germany

Semiconducting single crystals of the 6H-polytype of SiC were implanted with ⁵⁷Fe ions with nominal doses starting from 1x10¹⁶cm⁻² up to a highest dose of 2x10¹⁷cm⁻² at energies of 100 keV and 200 keV in order to produce a diluted magnetic semiconductor (DMS). After subsequent rapid thermal annealing at 1000^∘C the samples were investigated by x-ray diffraction (XRD), high-resolution cross-sectional transmission electron microscopy (HRTEM), superconducting quantum interference device (SQUID) and ⁵⁷Fe conversion electron Mössbauer spectroscopy (CEMS) at room temperature and 4.2 K. Our results prove unambigously that the main reason for the ferromagnetism in ⁵⁷Fe ion-implanted Silicon Carbide is the formation of epitaxial superparamagnetic Fe₃Si clusters which occurs for Fe concentrations above 3%. For the lowest dose of 1x10¹⁶cm⁻² we find evidence of ferromagntism below 20 K via a weak magnetic hyperfine interaction. We propose that the possibility exists to obtain a real DMS in Fe-implanted SiC for Fe concentraions in the range of 1-3%.