Programming language

Metamaterial

Engineering

Physical acoustics

Acoustic wave

Wave propagation

Physics

Spin wave

Structural engineering

Ferromagnetism

Mechanical wave

Rayleigh wave

Optics

Transverse wave

Acoustics

Quantum mechanics

Surface wave

Longitudinal wave

Curl (programming language)

Love wave

Computer science

Ion acoustic wave

Transverse plane

Condensed matter physics

Electromagnetism

Physical review. B./Physical review. B

We consider spin angular momentum density in inhomogeneous acoustic fields: evanescent waves and surface waves at interfaces with negative-density metamaterials. Despite being purely longitudinal (curl-free), acoustic waves possess intrinsic vector properties described by the velocity field. Motivated by the recent description and observation of the spin properties in elastic and acoustic waves, we compare these properties with their well-known electromagnetic counterparts. Surprisingly, both the transverse spin of evanescent waves and the parameters of surface waves are very similar in electromagnetism and acoustics. We also briefly analyze the important role of dispersion in the description of the energy and spin densities in acoustic metamaterials.

Transverse spin and surface waves in acoustic metamaterials