Preparation of Low Microwave Loss YIG Thin Films by Pulsed Laser Deposition

Y3Fe5O12 thin films with thickness 10 nm <= t <= 1440 nm were grown on Gd3Ga5O12 (111) substrates by pulsed laser deposition. The X-ray diffraction experiments confirmed the films are pure yttrium iron garnet (YIG) phase with preferred (111) orientation. The magnetic and microwave properties were studied as a function of film thickness by the dc magnetization and ferromagnetic resonance (FMR) measurements. The FMR linewidth (Delta H) was found to decrease with the increase in film thickness (10 nm <= t <= 45 nm), attaining a minimum value of Delta H-perpendicular to = 5 Oe and Delta H-parallel to = 6 Oe, for perpendicular and parallel resonance, and then rising with further increase in thickness. Acid etching experiments were performed to understand the mechanism contributing to Delta H. The increase in Delta H with thickness (t > 45 nm) may be explained in terms of extrinsic mechanisms, such as inhomogeneities present at the surface of the films. However, the decrease in Delta H with thickness (t < 45 nm) is believed to be due to the surface anisotropy effect. The films showed low coercivity values in the range of similar to 1.5-7 Oe, which is an indicator of good quality YIG films.