Surface-Plasmon-Polariton (SPP)-Like Acoustic Surface Waves on Elastic   Metamaterials
  We investigate the dispersion properties of the acoustic surface waves on surface of elastic metamaterials. With an analytical approach, we show that unconventional acoustic surface waves, with dispersion behaviors very similar to the electromagnetic surface plasmon polaritons (SPPs) on metal surfaces, can exist on the elastic metamaterials around the frequency at which the elastic Lam\'e's constants satisfy lambda+mu=0. Two typical elastic metamaterials are exemplified to demonstrate such peculiar acoustic surface waves. 
Ke Deng, Zhaojian He, Yiqun Ding, Heping Zhao, and Zhengyou Liu
cond-mat.mtrl-sci physics.class-ph