ELECTROMAGNETIC-EXCITATION OF ULTRASOUND IN MAGNETICALLY ORDERED DIELECTRICS

The electromagnetic excitation of sound in magnetically ordered dielec trics-ferro- and antiferromagnets-is investigated theoretically. It is shown that sound generation in dielectrics by the Lorentz mechanism ( displacement current) is much less efficient than in metals. The magne toelastic mechanism of sound excitation in dielectrics is just as effi cient as in metals, In antiferromagnets the amplitude of the excited s ound depends on the relaxation parameter in the magnetic subsystem. Th e sound excitation efficiency increases as the orientational phase tra nsition point or the ferromagnetic resonance frequency is approached. (C) 1997 American Institute of Physics.