Study of BixY 3-xFe 5O12 Thin Films Grown by Pulsed Laser Deposition

Epitaxial films of Bi Y3- Fe5O12 (Bi:YIG) have been grown on [111]-oriented gadolinium-gallium-garnet substrates, Gd3Ga5O12 (GGG), by pulsed laser deposition (PLD). Complete epitaxial substitution of the bismuth, Bi3Fe5O12 (BIG), was achieved at a growth temperature of 500 °C and an O2 atmosphere of 200 mTorr. The epitaxial nature of the films was indicated by the diffraction patterns from reflection high-energy electron diffraction (RHEED). X-ray diffraction (XRD) also showed that there were no peaks other than multiples of the (444) reflection. The Faraday rotation angle, θ F, of these films increases linearly with the Bi content x yielding θ F/x = -1.9 deg/µm at λ= 633 nm and T = 300 K. From magnetooptical Kerr measurements (MOKE) we conclude that the uniaxial anisotropy constant, K u, of the BIG film is positive, which could be due to the expansive stress caused by the difference in thermal expansion of the film and the substrate.