The Dirac degeneracy of band structures, along with the valley states after breaking, holds promising potential for robust signal processing. However, the conventional graphene structure only harbors a single pair of Dirac points, limiting its capacity for information storage and manipulation, and hindering its application in small-sized on-chip devices. In this study, we experimentally investigate S-graphene acoustic crystals that host two pairs of Dirac points and valleys. By examining the interplay between these multivalley pairs, we observe double-kink edge states that display $W$-type and $M$-type dispersions self-guiding at zigzag- and bearded boundaries in a single sample, respectively, eliminating the requirement of a cladding layer in conventional valley Hall effect. Additionally, benefiting from the increased degree of freedom, a superdirectional yet adjustable topological antenna is demonstrated by selectively exciting a specific valley branch. This research expands the degree of freedom for valleytronics and has the potential to stimulate the exploration of multiple spin-valley couplings and the design of unique functional devices.

• Received 29 August 2023
• Revised 6 December 2023
• Accepted 25 January 2024

DOI:https://doi.org/10.1103/PhysRevB.109.054109