A phenomenon exclusive to the propagation of acoustic waves has been identified, opening up new possibilities for the development of advanced communication technologies through acoustic devices.
The research was led by the Materials Research Institute at Tohoku University, in conjunction with the Japan Atomic Energy Agency and the RIKEN Center for Emergent Matter Science.
What are surface acoustic waves?
Surface acoustic waves (SAWs), elastic vibrations that travel along the surface of materials like ripples on a pond, play a fundamental role in current communication technologies. These elements are essential in frequency filters used in everyday devices such as mobile phones.
These devices transform electrical signals into vibrations or “ripples” through the piezoelectric effect, allowing for efficient signal processing. Therefore, a deeper understanding of the behavior of SAWs is crucial for the advancement of future technologies.
Innovation in nanofabrication
In the experiment, the team used advanced nanofabrication techniques to create a periodic array of magnetic materials on a nanoscale. This array can be considered as a specialized grid through which the waves pass.
Surprisingly, instead of the typical symmetric diffraction pattern, the team observed a completely new asymmetric diffraction phenomenon of SAWs, called “nonreciprocal diffraction”.
“This phenomenon had only been observed previously in optics,” says Yoichi Nii, “so we are very excited to confirm that it extends beyond optics to other wave phenomena.” Through theoretical analysis, the team identified this asymmetric behavior as a result of the unique interaction between SAWs and magnetic materials, specifically related to their angular moments.
This discovery may allow for precise control of SAW propagation paths using magnetic fields, leading to the development of innovative acoustic devices that enhance both classical and quantum communication technologies.
Investigating new properties of SAWs is essential for developing next-generation communication systems and devices.
The study was published in Physical Review Letters on January 14, 2025.
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