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MA: Fachverband Magnetismus

MA 16: Magnonics I

MA 16.10: Vortrag

Dienstag, 19. März 2024, 12:00–12:15, EB 107

Giant Surface Acoustic Wave Nonreciprocity in CoFeB/Ru/CoFeB Synthetic Antiferromagnets — •Matthias Küß¹, Stephan Glamsch¹, Mariam Hassan¹, Yannik Kunz¹, Andreas Hörner¹, Mathias Weiler², and Manfred Albrecht¹ — ¹Institute of Physics, University of Augsburg, 86135 Augsburg, Germany — ²Fachbereich Physik and Landesforschungszentrum OPTIMAS, RPTU Kaiserslautern-Landau, 67663 Kaiserslautern, Germany

Surface acoustic waves (SAWs) have made their way into many everyday devices. These "nano earthquakes" can be efficiently launched and detected on piezoelectric substrates with periodic metallic gratings. Resonant coupling of SAWs with spin waves (SWs) is the basis for an energy-efficient approach towards SW manipulation. In addition, magnetoacoustic interaction affects the properties of the SAW, which in turn can be used to devise new types of microwave devices.

Here, we investigate the SAW-SW interaction in a synthetic antiferromagnet (SAF) composed of two ferromagnetic layers separated by a thin nonmagnetic spacer layer. The low-frequency SW mode shows a large nonreciprocal SW dispersion f(+k) ≠ f(−k). Because of efficient coupling between this SW mode and the SAW, we observe large nonreciprocal SAW transmission in the piezoelectric/SAF hybrid device. We demonstrate that the SAW transmission nonreciprocity can be optimized to be giant (>100 dB) in CoFeB/Ru/CoFeB SAFs made out of low-damping CoFeB magnetostrictive layers, which holds potential for the realization of acoustic isolators [M. Küß et al., ACS Appl. Electron. Mater. 5, 5103 (2023)].

Keywords: Spin Waves; Magnetoacoustics; Surface Acoustic Waves; Nonreciprocity; Synthetic Antiferromagnet