First- and second-order magnetic anisotropy and damping of europium iron garnet under high strain

Abstract

Understanding and tailoring static and dynamic properties of magnetic insulator thin films is important for spintronic device applications. Here, we grow atomically flat epitaxial europium iron garnet (EuIG) thin films by pulsed laser deposition on (111)-oriented garnet substrates with a range of lattice parameters. By controlling the lattice mismatch between EuIG and the substrates, we tune the strain in EuIG films from the compressive to the tensile regime, which is characterized by x-ray diffraction. Using ferromagnetic resonance (FMR), we find that, in addition to the first-order perpendicular magnetic anisotropy which depends linearly on the strain, there is a significant second-order one that has a quadratic strain dependence. Inhomogeneous linewidth of the FMR increases notably with increasing strain, while the Gilbert damping parameter remains nearly constant $(\ensuremath{\approx}2\ifmmode\times\else\texttimes\fi{}{10}^{\text{--}2})$. These results provide valuable insight into the spin dynamics in ferrimagnetic insulators and useful guidance for material synthesis and engineering of next-generation spintronics applications.