Ultrathin bismuth-yttrium iron garnet films with tunable magnetic anisotropy
Phys. Rev. Materials 10, 034404 – Published 3 March, 2026
DOI: https://doi.org/10.1103/8l57-yqsx
Abstract
We report on the epitaxial growth of nm-thick films of bismuth-substituted yttrium iron garnet (BiYIG) by high-temperature off-axis radio-frequency magnetron sputtering. We demonstrate accurate control of the magnetic properties by tuning of the sputtering parameters and epitaxial strain on various (111)-oriented garnet substrates. BiYIG films with up to −0.80% lattice mismatch with the substrate remain fully strained up to 60 nm thick, maintaining a high crystalline quality. Transmission electron microscopy and energy-dispersive x-ray spectroscopy confirm coherent epitaxial growth, the absence of defects, and limited interdiffusion at the BiYIG/substrate interface. Varying the tensile or compressive strain between −0.80% and in BiYIG allows for accurate compensation of the total magnetic anisotropy through magnetoelastic coupling. The effective magnetic anisotropy of sputtered BiYIG films can be further tuned via the off-axis deposition angle and the oxygen flow during growth, which determine the cation stoichiometry. Under optimized growth conditions, a ferromagnetic resonance (FMR) linewidth of 1 mT at 10 GHz is reliably obtained even for thicknesses as low as 10 nm. We also report small FMR linewidths in ultrathin (2–5 nm) BiYIG films grown on diamagnetic substrate yttrium scandium gallium garnet. These findings highlight the promise of low-damping, strain-engineered nm-thick BiYIG films for implementing advanced functionalities in spin-orbitronic and magnonic devices. Specifically, the magnetic-anisotropy compensation and low damping enable large cone-angle magnetization dynamics immune to magnon-magnon nonlinear scattering.
