We report (001)-oriented FePtAg-C nanogranular films consisting of fine particle size of about 5 nm with a narrow size distribution of 3.3 nm in variance that were grown on a Fe-Ta-C nanocrystalline soft magnetic underlayer (SUL) through MgO/ SiO2 intermediate layers. The degree of L 10 order, c -axis orientation and resulting magnetic properties of FePtAg-C nanogranular films grown at low temperatures are improved by the post annealing effect without changing the nanogranular microstructure dramatically. Square-shaped perpendicular hysteresis loops with large negative nucleation field of 3.8 kOe, 100% squareness, coercivity of ∼8 kOe, and high energy barrier of 2.13 eV were obtained for the double-layered medium. Temperature dependent Kerr loops measurement reveals that the coercivity and nucleation field decrease at a rate of 26 Oe/°C and 20 Oe/°C, respectively. These results suggest that the (001) textured FePtAg-C nanogranular films with perpendicular anisotropy on SUL may be suitable as a recording medium to realize ultrahigh-density perpendicular recording in the conventional recording system.
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