Magnetic Properties and Domain Structures of Co-C Nanogranular Films Prepared by Pulsed Filtered Vacuum Arc Deposition
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Granular Co_xC_<1-x>(x=60, 65, 70 at.%)films were prepared by pulsed filtered vacuum arc deposition. Subsequent thermal annealing was performed in vacuum at various temperatures. The films were characterized by non-Rutherford backscattering spectrometry, Raman Spectroscopy, atomic force microscopy and magnetic force microscopy. Clear magnetic force microscopy images were only observed in the films after annealing at a sufficiently high temperature, indicating that there was perpendicular magnetic anisortropy in these films. The M-H hysteresis loops of the films were measured by a SQUID magnetometer. The optimum annealing temperature for the maximum coercivity was found to depend on the cobalt concentration. For a typical Co_<65>C_<35>sample of 20nm thick after annealing at 350℃ in vacuum for 1 hour, the saturation magnetization was 500 emu/cm^3, the coercivity was 460 Oe, and the ratio of the remanence to the saturation magnetization was 0.68 at 300K.
