Magnetization and ferromagnetic resonance studies in implanted and crystal ion sliced bismuth-substituted yttrium iron garnet films

Abstract

Bismuth-substituted yttrium iron garnet (Bi-YIG) is the material of choice in the fabrication of optical isolators. Recently some of us have demonstrated an ion-implantation based technique for detaching single-crystal Bi-YIG films from their gadolinium gallium garnet growth substrates, and for their subsequent bonding onto semiconductor wafers. In this article we study the magnetic properties of bubble-type Bi-YIG films with large out-of-plane uniaxial anisotropy in various stages of the separation process. We find that the implantation reduces the perpendicular anisotropy field from approximately 1435 to 750 Oe as a result of increased residual strain. Annealing partially restores the anisotropy to 900 Oe depending on annealing conditions. Chemical etching of the implanted sample separates the Bi-YIG film from the substrate at the sacrificial layer. Upon detachment the perpendicular anisotropy of the sample is nearly fully restored to its original value. The 9 GHz ferromagnetic resonance (FMR) linewidth of these films is large (440–520 Oe) and is only weakly affected by the processing.