Journal of Physics Condensed Matter
Propagation of ultrasound near the phase transition in Ising systems
A. Pawlak
Abstract
The effects of order-parameter strain coupling on the critical (tricritical) sound attenuation and dispersion are studied above T c in the elastically isotropic Ising model. Under free boundary conditions a cross-over in the behaviour of acoustic quantities to a 'strong-coupling' regime is predicted. New scaling relations for the critical attenuation and dispersion are obtained and the corresponding scaling functions are calculated using an ε-expansion. Non-asymptotic effects are also discussed.