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18/07/2023 - Séminaire - Dhagat Pallavi

Mardi 18 Juillet 2023 à 10h00, Dhagat Pallavi (Oregon State University, USA) donnera un séminaire à l’auditorium TRT.

Title :Analog RF Signal Processing with Magneto-acoustic Devices

Abstract :
Acoustic waves provide a means for modulating magnetic anisotropy in magnetostrictive materials for a variety of applications e.g., reconfigurable magnonics, and rf signal processing [1, 2]. This talk will focus on analog signal processing devices, in particular signal correlators and filters, in which significant power savings can be achieved. We will present experimental results for heterogeneously integrated high-overtone bulk acoustic wave resonators (HBARs), which can enable implementation of tunable rf filters [3]. The resonator is fabricated by transfer printing the acoustic transducer on a bulk yttrium-iron-garnet (YIG) substrate. In the region of cross-over between the acoustic wave and spin wave dispersion curves, the resonant acoustic modes are strongly attenuated and shifted in frequency due to hybridizing with spin waves to form coupled magneto-elastic waves. As spin wave dispersion is tunable by the applied bias magnetic field, the cross-over region is also tunable. Thus, filters with tunable in center frequency and bandwidth become possible to realize.
The signal correlator is a thin-film device, based on parametric pumping of spin waves by acoustic waves in a YIG thin film [4]. Here, the idler spin wave, generated to conserve energy and momentum in the interaction, manifests the correlation between the interacting acoustic and spin-wave signals. In these devices, YIG is chosen for its low damping of both spin and acoustic waves and magneto-elastic
properties for coupling them. The growth and integration of low-loss YIG on common semiconductor substrates, however, remains impractical. The magneto-elastic interactions in YIG are also weak. A goal of this presentation will be to stimulate a discussion on new materials and fabrication methods needed to enable novel microwave magnetic devices.

References :
[1] G. Volluet, Electronics Letters 13, no. 19, p. 588, 1977.
[2] A. J. Giarola, et al., Proceedings of the IEEE, v. 55, p. 593, 1967.
[3] V. Gokhale, et al., “Dynamic Mode Suppression and Frequency Tuning in S-band GaN/YIG Magnetoelastic HBARs,” IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, accepted, (2023)
[4] A. Jander, P. Dhagat and C. Rivard, Spin Mechanics VII Workshop, Germany, August 2022.

Short Biography : Dr. Pallavi Dhagat is a Professor in the School of Electrical Engineering and Computer Science at Oregon State University, USA. She holds a PhD in electrical engineering and an MBA degree. Her research focuses on novel characterization techniques and device applications for magnetic materials. She has authored over 60 peer-reviewed publications. Dr. Dhagat has served as the President of the IEEE Magnetics Society and is currently leading the development of an innovation engine in semiconductor technologies in the Pacific Northwest states of the United States.


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