Growth Induced Magnetic Anisotropy in Yttrium Iron Garnet Films on Yttrium Aluminum Garnet Substrates

Yttrium iron garnet (YIG) is a ferrimagnetic oxide of importance for a variety of applications including magnetic field sensors and microwave signal processing devices. Most of the applications, however, require a bias magnetic field that impedes miniaturization of YIG based sensors and communication devices. This work is aimed at strain engineering of YIG films to realize an induced magnetic anisotropy field that could act as a built-in bias field. We discuss here pulsed laser deposition (PLD) and characterization of YIG films on yttrium aluminum garnet (YAG) substrates. One expects the − 3% lattice mismatch between the film and substrate to result in an in-plane compressive strain and out-of-plane tensile strain. Films with thickness 55 nm to 380 nm were deposited on (100), (110), and (111) YAG substrates and annealed at high temperatures were characterized by structural and magnetic characterization techniques. The uniaxial out-of-plane strain anisotropy field estimated from X-ray diffraction data varied from 0.5 to 4.kOe for the films, showed an increase with increasing film thickness, and the highest values were for films on (100)YAG. Ferromagnetic resonance (FMR) measurements at 5 to 10 GHz also revealed the presence of a growth induced uniaxial anisotropy field as high as 450 Oe in the films, that decreased with increasing film thickness. The FMR line-width varied from 19.5 Oe to 82 Oe with films on (100) YAG showing the smallest values. The PLD YIG films on YAG substrates exhibiting a large perpendicular anisotropy field have the potential for use in sensors and high frequency devices.