Extended topological valley-locked surface acoustic waves

Here the authors provide experimental evidence of extended topological valley-locked states. By splicing together Dirac semimetals and topological insulators, they demonstrate reduced backscattering and enhanced matching of SAW with interdigital transducers proposing this system for topological acoustics devices. Stable and efficient guided waves are essential for information transmission and processing. Recently, topological valley-contrasting materials in condensed matter systems have been revealed as promising infrastructures for guiding classical waves, for they can provide broadband, non-dispersive and reflection-free electromagnetic/mechanical wave transport with a high degree of freedom. In this work, by designing and manufacturing miniaturized phononic crystals on a semi-infinite substrate, we experimentally realized a valley-locked edge transport for surface acoustic waves (SAWs). Critically, original one-dimensional edge transports could be extended to quasi-two-dimensional ones by doping SAW Dirac semimetal layers at the boundaries. We demonstrate that SAWs in the extended topological valley-locked edges are robust against bending and wavelength-scaled defects. Also, this mechanism is configurable and robust depending on the doping, offering various on-chip acoustic manipulation, e.g., SAW routing, focusing, splitting, and converging, all flexible and high-flow. This work may promote future hybrid phononic circuits for acoustic information processing, sensing, and manipulation.

Automated summary

The authors provide experimental evidence for extended topological valley-locked states and propose their application in acoustics devices. By combining Dirac semimetals and topological insulators, they demonstrate reduced backscattering and improved matching of surface acoustic waves (SAWs) with interdigital transducers. Through the design and manufacturing of miniaturized phononic crystals on a semi-infinite substrate, they successfully realize valley-locked edge transport for SAWs. This work has important implications for future acoustic information processing, sensing, and manipulation.