FePt–Ag nanocomposite film with perpendicular magnetic anisotropy

Magnetic properties of FePt–Ag nanocomposite films synthesized by annealing $(\mathrm{FePt}/\mathrm{Ag}{)}_n$ multilayers deposited on a MgO(100) substrate by laser ablation are discussed in conjunction with the structure. After annealing over a temperature range from 540 to 650 °C, a large perpendicular magnetic anisotropy constant $K_u$ of the order of ${10}^7\hspace{0.17em}\mathrm{erg}/\mathrm{cc}$ developed. The so-called $\mathrm{\delta M}$ curve measurements imply that grains are magnetically decoupled. Increasing the Ag layer thickness is found to be useful for the improvement of the (001) orientation of FePt grains. The remanence ratio and coercivity increase with a rise in the annealing temperature. Magnetic grains of less than 10 nm and a small activation volume of the order of ${10}^{\text{−19}}\hspace{0.17em}{\mathrm{cm}}^3$ are observed.