New magnetoacoustic modes in YIG substrates

Previously unreported magnetoacoustic modes have been detected on the surface of a 1.5 x 0.1 cm2 YIG disk. The waves were excited by meander-line pairs along the [100] and [011] directions on a (01 anti 1) surface. The meander line excited both a magnetoelastic Rayleigh wave and the new modes for both the [100] and [011] directions. A drop of water on the surface of the substrate was used to absorb the energy in the surface wave modes while the velocity and dispersion of the new mode were being examined. For the [100] direction the new modes were approximately 8bdm down from the surface wave, while for the case of the [011] direction nearly all of the energy was carried in the new modes. The velocity of the surface wave was (v/sub s//1.07) x (1 +- 0.015) (i.e., within 1.5 percent of the theoretical value) while the velocity of the first of the new modes was v/sub s/(1 +- 0.0) for the [100] direction and is dispersive for the [011] direction. If the excitation frequency is held constant the maximum amplitude of the new wave is excited at approximately 20 G above the magnetic field which produces the maximum excitation for the surface wave. For excitation along the [011] direction, the new wave splits into two modes for magnetic fields between 300 and 330 G. The new mode could also be excited by a Rayleigh wave produced by IDT's on a ZnO film for the [100] direction