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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.
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Tunable Non-Reciprocal Phase Shifter and Spin-Coated Ferrites for Adaptive Microwave Circuits
Tunable non-reciprocal components with ferrites that can be integrated using a foundry suitable process are key to achieving low-power adaptive microwave circuits. The current state-of-the-art still relies on electrical tuning or resistive absorbers to facilitate unidirectional propagation. Here, we demonstrate a novel process for spin-coating thick films of ferrites without the complexities of vacuum processes or high-temperature annealing. Composites of yttrium iron garnet (YIG) nanoparticles in a matrix spin-on-glass are spin-coated on silicon substrates, and magnetic properties comparable to bulk YIG are obtained in films exceeding 30 microns. We also propose a design for tunable phase shifter based on periodically serrated coplanar waveguide with a YIG cladding. A nonreciprocal phase difference of 20 – 60 degrees is obtained over a tunable band of 550 MHz between 3.85 - 4.4 GHz from a tuning magnetic field of 8 – 40 kA/m.
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- Award ID(s):
- 1719875
- PAR ID:
- 10411974
- Date Published:
- Journal Name:
- 2023 International Microwave and Antenna Symposium (IMAS)
- Page Range / eLocation ID:
- 62 to 65
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/IMAS55807.2023.10066899
