Ultrathin bismuth-yttrium iron garnet films with tunable magnetic anisotropy

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 +0.56\% in BiYIG allows for accurate compensation of the total magnetic anisotropy through magneto-elastic 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.

References in corpus (14)

• Magnetization oscillations and waves driven by pure spin currents
• Ultra Thin Films of Yttrium Iron Garnet with Very Low Damping: A Review
• Systematic Control of Strain-Induced Perpendicular Magnetic Anisotropy in Epitaxial Europium and Terbium Iron Garnets Thin Films
• True amplification of spin waves in magnonic nano-waveguides
• A First Principle Study on Magneto-Optical Effects and Magnetism in Ferromagnetic Semiconductors Y${}_3$Fe${}_5$O${}_{12}$ and Bi${}_3$Fe${}_5$O${}_{12}$
• X-ray interference effects on the determination of structural data in ultrathin La2/3Sr1/3MnO3 epitaxial thin films
• First and second order magnetic anisotropy and damping of europium iron garnet under high strain
• Orbital Pumping in Ferrimagnetic Insulators
• Composition-tunable magnon-polaron anomalies in spin Seebeck effects in epitaxial Bi${}_x$Y${}_{3-x}$Fe${}_5$O${}_{12}$ films
• Atomic Layer Deposition of Yttrium Iron Garnet Thin Films for 3D Magnetic Structures
• Lattice-tunable substituted iron garnets for low-temperature magnonics
• Temperature-independent ferromagnetic resonance shift in Bi-doped YIG garnets through magnetic anisotropy tuning
• Current-Controlled Magnon-Magnon Coupling in an On-Chip Cavity Resonator
• Observation and Control of Chiral Spin Frustration in BiYIG Thin Films

Cited by in corpus (2)

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