Extended Data Fig. 3: Different EFC properties attained by engineering the surface terminations of the Weyl phononic crystal. | Nature

Extended Data Fig. 3: Different EFC properties attained by engineering the surface terminations of the Weyl phononic crystal.

From: Topological negative refraction of surface acoustic waves in a Weyl phononic crystal

Extended Data Fig. 3

a, Surface EFCs evaluated for the XZ surfaces at the Weyl frequency of 5.75 kHz, where the parameter dy defined at the top of the column characterizes the surface truncation (black dashed line). The grey regions display the projections of bulk bands, the blue spheres display the projections of the Weyl points K and K′ at 5.75 kHz, and the arrows indicate the directions of the group velocities for the surface arc states. b, Similar to a, but for the YZ surfaces specified by dx. The evolution of the EFCs for different surface terminations shows various possibilities of manipulating the surface states according to their group velocities. We focus on the cases in a2, a4 and b4 in the main text to attain the desired SAW properties. Throughout, we use 5.75 kHz to shrink the momentum regions projected by the bulk bands, which is favourable for the experimental observation of the surface arc states and the associated interfacial phenomena.

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