Growth of Perpendicular Magnetic Anisotropy in Gallium-substituted Yttrium Iron Garnet Thin Films

We investigate the effect of Ga substitution on the magnetic properties of nanometer-thin Ga:YIG (Y_3Fe_5-xGa_xO_12) films grown by liquid phase epitaxy (LPE) [1,2]. The Ga content was varied between 1.1–1.3 f.u. and film thicknesses were 30 to 230 nm. The substitution of Fe sites by Ga ions reduces the remanent magnetization. Together with the tensile strain it causes a stronger out-of-plane uniaxial anisotropy (PMA) making thin Ga:YIG films perpendicularly magnetized. We also demonstrate that, independent of the thickness and of the substrate orientation, i.e. GGG(111) vs. (001), the PMA gradually increases with the Ga-content, resulting in a 14 times larger perpendicular anisotropy for the highest Ga content used in this study compared to pure YIG. This allows for an easy tuning of the PMA by variation of the Ga concentration. One feature of YIG almost remains: the Gilbertdamping increases only slightly with the amount of Ga. The inhomogeneous broadening shows a stronger dependence.