Crystallization and stability of rare earth iron garnet/Pt/gadolinium gallium garnet heterostructures on Si

Abstract

The crystallization of rare earth iron garnet films such as dysprosium iron garnet on Si substrates provides a path for integration of these complex oxides into magnetic devices. We report the growth of 50–75 nm thick dysprosium yttrium iron garnet (YDyIG) films, deposited without a seed layer then crystallized by a 750 °C rapid thermal anneal, forming a polycrystalline film with grains of several µm diameter containing radiating low-angle boundaries. The Y:Dy ratio affects the magnetization and anisotropy of YDyIG. Crystallization becomes more challenging as the garnet film thickness decreases. To crystallize thinner rare earth garnet films, tri-layer stacks consisting of a 50 nm thick gadolinium gallium garnet (GGG) seed layer, a 1.5 nm thick Pt diffusion barrier, and a 10 nm thick YDyIG film were prepared. The YDyIG/Pt/GGG tri-layers showed agglomeration of the Pt leading to a morphology consisting of a polycrystalline garnet film enriched with Dy and Fe and containing a layer of Pt nanoparticles embedded near its surface.