EMISSION OF GHZ SHEAR-WAVES BY FERROELASTIC DOMAIN-WALLS IN FERROELECTRICS

The 90-degrees domain walls and comparable ferroelectric domain walls are strong sound emitters in the GHz range. The elastic medium on both sides of the domain wall with its mass and elastic properties is a quasi-infinite transmission line into which the sound is emitted. This emission causes a strong dielectric dispersion at GHz frequencies and may form the basis for many dispersive effects in this frequency range which were observed during the last 40 years in many ferroelectric and even some magnetic materials. A simple elastic-electric equivalent circuit describes the mechanism of sound emission.