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The origin of ferromagnetism in 57Fe ion-implanted semiconducting 6H-polytype silicon carbide

Stromberg, F.; Keune, W.; Chen, X.; Bedanta, S.; Reuther, H.; Mücklich, A.
Semiconducting (mostly p-doped) single crystals of the 6H-polytype of α-SiC(0001) were implanted with 57Fe ions with a nominal dose of 1.0 × 1016, 2.0 × 1016, 3.0 × 1016 or 2.0 × 1017 cm−2 (high-dose sample phd) at 100 or 200 keV ion energy in order to produce diluted magnetic semiconductors (DMSs). After implantation all samples (except p-hd) were subject to rapid thermal annealing at 1000 ◦C for 2 min. The structure was investigated by x-ray diffraction, high-resolution cross-sectional transmission electron microscopy and sputter-Auger depth profiling. The magnetic properties were obtained from superconducting quantum interference device (SQUID) magnetometry and 57Fe conversion electron M¨ossbauer spectroscopy (CEMS) at room temperature (RT) and 4.2 K. Our combined results obtained by several techniques prove unambiguously that ferromagnetism in 57Fe-implanted SiC for Fe concentrations above 3%originatesmostly from epitaxial superparamagnetic Fe3Si (and possibly a small fraction of Fe nanoparticles) in the SiC matrix. We find a wide range of blocking temperatures, TB, which start from 400 K for a dose of 2.0 ×1016 cm−2, and shift downwards to ∼220 K for 3.0× 1016 cm−2. For the lowest dose of 1.0 × 1016 cm−2 at 200 keV, we find evidence of ferromagnetism below 20 K via weak magnetic hyperfine interaction. Our measurements suggest that for a maximum Fe concentration in the range of 1–3%, which corresponds to this lowest Fe dose, the possibility exists to obtain a DMS in Fe-implanted SiC, prepared at lower or equal implantation doses.


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Publ.-Id: 8936