Magnetic and Microstructural Properties of [FePt–Mg(Ti, Ta, Zr, Nb, B)O] Granular Films

Magnetic and microstructural properties of granular FePt films mixed with a novel Mg(Ti, Ta, Zr, Nb, B)O multiple-oxide segregant material were investigated. Two different series of samples were prepared. In series (I), a Mg(Ti, Ta, Zr, Nb, B)O(t) (t = 2, 4, and 6 nm) interlayer was deposited under a 10 nm-thick FePt layer; in series (II), FePt(2 nm)/[Mg(Ti, Ta, Zr, Nb, B) O(t)/FePt(4 nm)]
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(t = 0.5, 1, and 1.5) multilayer stacks consisting of FePt films interleaved with Mg(Ti, Ta, Zr, Nb, B)O layers were prepared. Overall, the granular FePt films present a preferential perpendicular anisotropy, the coercivity being, however, lower than that of the reference FePt films, likely because of diffusion of metallic elements from the segregant interlayer into the FePt grains. Such an effect is more extended in sample series (II) because of the multilayer structure, and lower coercivity values are achieved. However, using a multilayer stack allows obtaining FePt films with a better (001) crystallographic texture and a dense dome-like morphology that is closed to the expected columnar grain structure, thus indicating that such a strategy and the proposed segregant material are of potential interest for the development of the FePt-based magnetic recording media.