Sub-micrometer yttrium iron garnet LPE films with low ferromagnetic resonance losses

Abstract

Using liquid phase epitaxy (LPE) technique (111) yttrium iron garnet (YIG)\nfilms with thicknesses of ~100 nm and surface roughnesses as low as 0.3 nm have\nbeen grown as a basic material for spin-wave propagation experiments in\nmicrostructured waveguides. The continuously strained films exhibit nearly\nperfect crystallinity without significant mosaicity and with effective lattice\nmisfits of delta a(perpendicular)/a(substrate) ~10-4 and below. The\nfilm/substrate interface is extremely sharp without broad interdiffusion layer\nformation. All LPE films exhibit a nearly bulk-like saturation magnetization of\n(1800+-20) Gs and an `easy cone' anisotropy type with extremely small in-plane\ncoercive fields <0.2 Oe. There is a rather weak in-plane magnetic anisotropy\nwith a pronounced six-fold symmetry observed for saturation field <1.5 Oe. No\nsignificant out-of-plane anisotropy is observed, but a weak dependence of the\neffective magnetization on the lattice misfit is detected. The narrowest\nferromagnetic resonance linewidth is determined to be 1.4 Oe @ 6.5 GHz which is\nthe lowest value reported so far for YIG films of 100 nm thicknesses and below.\nThe Gilbert damping coefficient for investigated LPE films is estimated to be\nclose to 1 x 10-4.\n