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Hybrid elastic solids


Metamaterials can exhibit electromagnetic and elastic characteristics beyond those found in nature. In this work, we present a design of elastic metamaterial that exhibits multiple resonances in its building blocks. Band structure calculations show two negative dispersion bands, of which one supports only compressional waves and thereby blurs the distinction between a fluid and a solid over a finite frequency regime, whereas the other displays ‘super anisotropy’ in which compressional waves and shear waves can propagate only along different directions. Such unusual characteristics, well explained by the effective medium theory, have no comparable analogue in conventional solids and may lead to novel applications.

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Figure 1: Physical model and a practical design.
Figure 2: Band structure and effective medium parameters.
Figure 3: Field distributions of some specific eigenstates.
Figure 4: Transmission through a finite sample.


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We thank Z. Hang and I. Tsukerman for useful discussions. This work was supported by Hong Kong RGC Grant No. 605008 and RGC Grant HKUST604207.

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Y.L. and Y.W. carried out the research and contributed equally. P.S. and Z-Q.Z. supervised the research and contributed to its design. All the authors discussed the results extensively.

Corresponding author

Correspondence to Zhao-Qing Zhang.

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The authors declare no competing financial interests.

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Lai, Y., Wu, Y., Sheng, P. et al. Hybrid elastic solids. Nature Mater 10, 620–624 (2011).

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