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Acoustically driven ferromagnetic resonance (ADFMR) is a platform that enables efficient generation and detection of spin waves via magnetoelastic coupling with surface acoustic waves (SAWs). While previous studies successfully achieved ADFMR in ferromagnetic metals, there are only few reports on ADFMR in magnetic insulators such as yttrium iron garnet (Y3Fe5O12, YIG) despite more favorable spin wave properties, including low damping and long coherence length. The growth of high-quality YIG films for ADFMR devices is a major challenge due to poor lattice-matching and thermal degradation of the piezoelectric substrates during film crystallization. In this work, we demonstrate ADFMR of YIG thin films on LiNbO3 (LNO) substrates. We employed a SiOx buffer layer and rapid thermal annealing for crystallization of YIG films with minimal thermal degradation of LNO substrates. Optimized ADFMR device designs and time-gating measurements were used to enhance the ADFMR signal and overcome the intrinsically low magnetoelastic coupling of YIG. YIG films have a polycrystalline structure with an in-plane easy direction due to biaxial stresses induced during cooling after crystallization. The YIG device shows clear ADFMR patterns with maximum absorption for H ≈ 160 mT parallel to SAW propagation, which is consistent with our simulation results based on existing theoretical models. These results expand possibilities for developing efficient spin wave devices with magnetic insulators. 

Cerium-substituted yttrium iron garnet (Ce:YIG, Ce0.9Y2.1Fe5O12) was epitaxially grown on a (111)-oriented yttrium aluminum garnet (YAG) substrate using radio frequency ion beam sputtering. Magnetic hysteresis loops, transmissivity spectra, and magnetooptical (MO) responses, including Faraday rotation and Faraday ellipticity, were measured. The structural properties of the grown Ce:YIG were characterized using the x-ray rocking curve, reciprocal space map, pole figure, and x-ray reflectivity. X-ray photoelectron spectrometry revealed a dominant Ce3+ state in the grown Ce:YIG, but the transmission electron microscopy images showed columnar growth of Ce:YIG. This study demonstrates integration of epitaxial Ce:YIG on YAG, marking a significant step toward the fusion of MO garnets and laser crystals. 

Abstract Iron garnets that combine robust perpendicular magnetic anisotropy (PMA) with low Gilbert damping are desirable for studies of magnetization dynamics as well as spintronic device development. This paper reports the magnetic properties of low‐damping bismuth‐substituted iron garnet thin films (Bi_0.8Y_2.2Fe₅O₁₂) grown on a series of single‐crystal gallium garnet substrates. The anisotropy is dominated by magnetoelastic and growth‐induced contributions. Both stripe and triangular domains form during field cycling of PMA films, with triangular domains evident in films with higher PMA. Ferromagnetic resonance measurements show damping as low as 1.3 × 10⁻⁴with linewidths of 2.7 to 5.0 mT. The lower bound for the spin‐mixing conductance of BiYIG/Pt bilayers is similar to that of other iron garnet/Pt bilayers. 

Yttrium iron garnet (YIG) and barium titanate (BTO) were co-deposited on (001)-orientated gadolinium gallium garnet substrates by pulsed laser deposition with composition determined by the ratio of laser shots ablating each target. With increasing shot ratios of YIG/BTO = 2.5/1, 4/1, 20/1, and 30/1, the majority phase in the film changes from textured polycrystalline perovskite to epitaxial garnet. Cross-sectional STEM characterization of the YIG-rich films reveals three distinct sublayers: the bottom layer is a coherent epitaxial garnet layer with higher unit cell volume than that of YIG; the second layer is garnet exhibiting crystalline defects and misorientation; and the upper layer is amorphous. Highly defective regions within the second layer are richer in Ba, suggesting that the microstructure is promoted by the insolubility of Ba in YIG. Temperature-dependent magnetization measurements fitted to a super-exchange dilution model indicate the presence of nonmagnetic Ti and vacancies in both octahedral and tetrahedral sites. 

We use density functional theory (DFT) calculations to show that oxygen vacancies (vO) and mobility induce noncentrosymmetric polar structures in SrTi1−x−yFexCoyO3−δ (STFC, x=y=0.125) with δ={0.125,0.25}, enhance the saturation magnetization, and give rise to large changes in the electric polarization |ΔP|. We present an intuitive set of rules to describe the properties of STFC, which are based on the interplay between (Co/Fe)-vO defects, magnetic cation coordination, and topological vacancy disorder. STFC structures consist of layered crystals with sheets of linearly organized O4,5,6-coordinated Fe–Co pairs, sandwiched with layers of O5-coordinated Ti. (Co/Fe)-vO defects are the source of crystal distortions, cation off-centering and bending of the oxygen octahedra which, considering the charge redistribution mediated by vO and the cations’ electronegativity and valence states, triggers an effective electric polarization. Oxygen migration for δ=0.125 leads to |ΔP|>∼10 µC/cm2 due to quantum-of-polarization differences between δ=0.125 structures. Increasing the oxygen deficiency to δ=0.25 yields |ΔP|, the O migration of which resolved polarization for δ=0.25 is >∼3 µC/cm2. Magnetism is dominated by the Fe,Co spin states for δ=0.125, and there is a contribution from Ti magnetic moments (∼1 μB) for δ=0.25. Magnetic and electric order parameters change for variations of δ or oxygen migration for a given oxygen deficiency. Our results capture characteristics observed in the end members of the series SrTi(Co,Fe)O3, and suggest the existence of a broader set of rules for oxygen-deficient multiferroic oxides.