MICROWAVE PHONON ATTENUATION IN YTTRIUM IRON GARNET

We report some microwave ultrasonic attenuation measurements at 9155 MHz on pure single-crystal yttrium iron garnet (YIG) which we believe determine the intrinsic attenuation in this material. Previous measurements on YIG by other workers were complicated by spurious effects. Our measurements are compared with current theories of attenuation by phonon-phonon interactions using the recently measured third-order elastic constants of YIG. The agreement found is about the same as in many other materials, which suggests that the intrinsic attenuation in YIG is understood and is caused by interactions with thermal phonons. © 1968 The American Institute of Physics.