Ferromagnetic (LaSr)MnO3 Films Deposited by RF Sputtering

Abstract

We prepared polycrystalline films of perovskite-type lanthanum manganese oxide La_1-x Sr _x MnO₃ (0≤x≤1) by RF diode sputtering, and investigated their structural, magnetic and magneto-optical properties. Crystalline films were easily grown during sputtering at relatively low substrate temperature (≥170°C). The films as crystallized in situ were poorer in crystallinity, and much smaller in saturation magnetization compared to bulk samples. By annealing the films in O₂ atmosphere above 900°C, the saturation magnetization increased and approached the values of bulk samples. Magnetization was aligned perpendicular to the film plane when the film with x=0.21 (which was sputter-deposited in mixed gas of Ar:O₂=9:1 on a GGG substate at 500°C) was annealed in air at 800°C. Faraday rotation F and ellipticity X increased at higher photon (h v) energy range. F of the film annealed in O₂ atmosphere at 900°C formed a peak at h v=2.9 eV, reaching -2.6×10⁴ deg/cm. X of the film reached -5.0×10⁴ deg/cm at h v=3.1 eV. The lanthanum manganese oxide film is a candidate for magneto-optical recording media using Kerr effect at short wavelength.