Pseudomorphic spinel ferrite films with perpendicular anisotropy and low damping

We report on epitaxial thin films of spinel ferrite Ni0.65Zn0.35Fe1.2Al0.8O4 with strain-induced perpendicular magnetic anisotropy (PMA) and low magnetic damping. Static magnetometry and broadband ferromagnetic resonance experiments show a distinct change in the preferred direction of magnetization from in-plane to out-of-plane when the coherent strain in films changes from ∼2% compressive on (001) MgAl2O4 to ∼0.5% tensile on (001) MgGa2O4 substrates. Significant deviations from the spin-only value (2.0) of the g-factor suggest spin-orbit effects and further support our conclusion of strain-driven magnetic anisotropy in these films. The low Gilbert damping parameter of α = 5 × 10−3 in these ferrite films, combined with their PMA, makes them promising for spintronic and frequency-agile microwave device applications.