A new kind of interface wave at twisted boundary of cubic crystal

The propagation of interface waves at twisted basal-plane boundary of cubic crystal is investigated by using analytic and numerical methods. The exact explicit secular equation for the bisector propagation direction is derived. In addition to the localized interface acoustic wave, earlier considered by Lim, Musgrave and Tholen, a new solution of the secular equation of leaky wave (LIAW) type has been found. It has been shown that the structure of the leaky wave solution depends on the anisotropy ratio of the crystal η. Usually LIAW is intermediated between the SH and SV bulk waves and its structure is similar to that of pseudosurface wave, propagating on the free surface of cubic crystal (PSM). But if η<2 and also the twisted angle θ>θ_cr, then the velocity of LIAW is greater then the velocity of shear vertical wave and the solution is similar to the high frequency pseudo-surface mode (HFPSM)