On asymmetric propagation on transverse acoustic waves near the structural phase transition in RbH3(SeO3)2

Abstract Recently ultrasonic measurements of the RbH 3 (SeO 3 ) 2 crystal have shown that a transverse acoustic wave propagating along the modulation axis of the incommensurate structure ( c -axis) and polarized along the polar axis ( b -axis) exhibits greater temperature anomalies of its velocity and damping than a wave propagating along the b -axis and polarized along the c -axis. The possible explanation of this experimental result is given on the basis of the Landau theory.