Reviewed by Lexie CornerJan 30 2025
Researchers from the Institute for Materials Research at Tohoku University, in collaboration with the Japan Atomic Energy Agency and the RIKEN Center for Emergent Matter Science, have identified a new acoustic wave propagation phenomenon with applications in acoustic-based communication technologies. Their findings were published in Physical Review Letters.
New diffraction phenomenon of acoustic waves. A novel asymmetric diffraction has been achieved using a nano-patterned array of ferromagnets. This demonstration arises from a unique interaction between ferromagnets and acoustic waves. Image Credit: Nii et al.
Surface acoustic waves (SAWs) are elastic vibrations that propagate along a material’s surface and are widely used in frequency filters for signal processing in mobile communication systems. These devices utilize the piezoelectric effect to convert electrical signals into mechanical vibrations for efficient signal transmission and filtering.
In this study, the researchers fabricated a periodic array of nanoscale magnetic materials using advanced nanofabrication techniques. As SAWs traveled through the structured magnetic array, it functioned as a diffraction grating, altering the wave propagation characteristics.
The results showed a nonreciprocal diffraction pattern, deviating from the expected symmetric diffraction typically observed in SAW systems.
This phenomenon has previously been observed only in optics, so we are very excited to confirm that it extends beyond optics to other wave phenomena.
Yoichi Ni, Institute for Materials Research, Tohoku University
Theoretical analysis confirmed that this asymmetry originates from the interaction between SAWs and the magnetic materials, particularly the influence of their angular momenta on wave propagation.
The ability to control SAW propagation paths using magnetic fields introduces new possibilities for acoustic device design. These findings provide a framework for developing next-generation acoustic components for classical and quantum communication systems, where precise wave manipulation is required.
Journal Reference:
Nii, Y., et al. (2025) Observation of Nonreciprocal Diffraction of Surface Acoustic Wave. Physical Review Letters. doi.org/10.1103/physrevlett.134.027001.