Magnetically Compensated Nanometer-thin Ga-Substituted Yttrium Iron Garnet (Ga:YIG) Films with Robust Perpendicular Magnetic Anisotropy

Abstract: Magnetically full or partially compensated insulating ferrimagnets with perpendicular magnetic anisotropy (PMA) offer valuable insights into fundamental spin-wave physics and high-speed magnonic applications. This study reports on key magnetic parameters of nanometer-thin Ga substituted yttrium iron garnet (Ga:YIG) films with saturation magnetization 4PiMs below 200 G. Vibrating sample magnetometry (VSM) is used to determine the remanent magnetization 4PiMr and the polar orientation of the magnetic easy axis in samples with very low net magnetic moments. Additionally, the temperature dependence of the net magnetization of magnetically compensated Ga:YIG films, with compensation points Tcomp near room temperature is investigated. For films with remanent magnetization values below 60 G at room temperature, the compensation points Tcomp are determined and correlated with their Curie temperatures TC. Ferromagnetic resonance (FMR) measurements at 6.5 GHz show that the FMR linewidths Delta H FWHM correlate inversely proportional with the remanent magnetization. The reduced saturation magnetization in the Ga:YIG films leads to a significant increase in the effective magnetization 4PiMeff and thus enables films with robust PMA. This opens up a new parameter space for the fine-tuning of potential magnonic spin-wave devices on commonly used GGG substrates.