Thermal Spin-Current Generation in Bi-Substituted YIG Films with Perpendicular Magnetic Anisotropy

In this study, we present a systematic investigation of perpendicular magnetic anisotropy and spin dynamics in bismuth-substituted yttrium iron garnet (Bi:YIG) films grown on SGGG[111] substrates using pulsed laser deposition. The films' thickness ranges from 5 nm to 20 nm. Structural characterization, employing X-Ray Diffraction and High-Resolution Transmission Electron Microscopy, shows that the film growth is epitaxial. All the films exhibit a perpendicular magnetic anisotropy component. Additionally, we analyzed the films by performing thermo-spin measurements in on-chip devices. Considering the device's geometry, we successfully quantified the spin Seebeck coefficient and the generated spin current within a Bi:YIG/Pt bilayer. The obtained value of the spin Seebeck coefficient is comparable to conventional YIG/Pt, affirming the potential of this material for efficient spin current generation as an insulating oxide with perpendicular magnetic anisotropy.