Surface Acoustic Waves Propagating In Magneto-electric Materials

As the combination of acoustic and electronic devices, surface acoustic wave (SAW) deviceshave board application prospects in the fields of frequency control, frequency selection, signalacquisition and processing, etc. With the miniaturization, high reliability and good anti-jammingcapacities of military and civilian electronic systems, SAW devices are becoming a hot research athome and abroad.To improve and enhance the performance of magnetoelectric SAW devices, it is significanceto determine the dispersion relation and different boundary conditions, and also important to studythe effects of biasing, the material properties of layer and substrate on the propagation of SAW.Based on the linear piezomagnetic-piezoelectric theory, we research four issues on Rayleigh wavespropagating in magneto-electric materials.(1) Considering the effects of Coriolis and centrifugal forces, we investigate an infinitemagnetoelectric plate which rotates at a constant angular rate about the thickness axe. The phasevelocity equations of the mode are obtained for electrically and magnetically open and shortedcases, respectively. The dispersion characteristic curves under non-rotating condition are consistentwith other studies that had been done, which verifies the correction of theoretical derivation andprocedures. Furthermore, the angular rate can affect the phase velocity, and the propagation ofSAW will changed by the poling direction.(2) We study surface acoustic waves propagating along the surface of a magnetoelectricsemi-infinite rotating about arbitrary directions, focusing on the cases of rotating about three axesand three coordinate planes. The impact angular rate to phase velocity will change as rotation axisvaries, we can get the position of rotation axis when the wave speed is most sensitive andinsensitive to rotation. Meanwhile, the phase velocity of Rayleigh wave and BG wave can beobtained, which are close to existing.(3) The propagation of Rayleigh wave under four different boundary conditions isinvestigated for a piezomagnetic layer on a piezoelectric half space structure. The dispersionequations are presented explicitly for the said boundary conditions, and we find the magneticboundary conditions dominate the propagation properties of the Rayleigh wave. The numericalresult shows: the wave speed will reduce evidently with the increase of piezomagnetic coefficient,and the influence of magnetic permeabilities of piezoelectric materials on the phase velocity can beneglected.(4) Under the base of above, we study shear-horizontal (SH) waves in a Y-cut quartz platecarrying an isotropic elastic layer. The accurate dispersion relations of elastic layer existence andnot present is obtained with boundary conditions. We use long-wave appropriate (wavelength ismuch larger than thickness of plate) and thin-film appropriate (the elastic layer is very thin) to compare to the above accurate situation, and find the thin-film appropriate is very accurate.