Critical Thickness of Yttrium Iron Garnet Thin Films with Epitaxial Interface to Get Perpendicular Magnetic Anisotropy

Minimizing the film thickness is the foundation to make devices smaller for practical applications. Here, we explore the critical thickness of yttrium iron garnet (YIG) films to obtain perpendicular magnetic anisotropy and analyze the mechanism behind. YIG film with robust perpendicular magnetic anisotropy and fine epitaxial interface is prepared. The effective field is as large as -1396 and -1758 Oe in 3.6 and 6 nm YIG films, respectively, indicating large perpendicular magnetic anisotropy in these two films. More importantly, the large strain-induced in-plane cubic magnetic anisotropy field of about 2068 Oe in 3 nm thick film is the main cause of the decay in perpendicular magnetic anisotropy. The YIG thickness at 3.6 nm is the minimum perpendicular in YIG films grown on YSGG substrates.