Magnetic Anisotropy of Yttrium Iron Garnet from Density Functional Theory

For applications in magnetic memory and spintronic devices, ferrimagnetic insulators (FMIs) with perpendicular magnetic anisotropy (PMA) are of special interest. Because of its low magnetic losses, yttrium iron garnet (Y3Fe5O12, also known as YIG) is frequently regarded as the most promising FMI film. However, YIG films typically have an in-plane easy axis, which limits their potential applications. In YIG films, several strategies are suggested to obtain PMA. In YIG and doped YIG films, the epitaxial strain brought on by lattice mismatch has proven to be a successful method for achieving PMA. The investigation on the theoretical mechanism of PMA induction has not yet been reported, even though PMA has been successfully induced in YIG and other FMIs films. In this study, density functional theory has been used to systematically examine the effects of mechanical strain, including in plane biaxial strain and out-of-plane strain, on magnetic anisotropy energy (MAE) in YIG and bismuth-doped YIG (BiYIG). The findings demonstrate that unstrained YIG has no magnetic anisotropy. Additionally, it has been found that the easy axis of the YIG may be changed from being in-plane to being out-of-plane by an out-of-plane compressive strain or a modest tensile in-plane biaxial strain. From the examination of the electronic structure, it has been observed that the local density of states close to the Fermi energy is mostly responsible for the shift in MAE. It is anticipated that the modulation of PMA in YIG and the design of spin wave devices based on YIG will both benefit from these results.