Temperature dependence of electromagnetically excited sound in single crystals of Fe

Abstract

The temperature dependence of the transmission of 9.4-GHz longitudinal sound through an (110)-oriented iron single crystal has been measured over the temperature range 4.2-310 K. The ~ 19-j.lm-thick crystal formed part of the common wall between two microwave cavities. A static magnetic field was maintained along the [111] direction in the plane of the sample and paranel to the incident rf magnetic field. The sound was generated through the Lorentz force on the rf currents associated with the incident microwaves. The transmission signal was -lO-13 W for incident microwave power of 200 m W. Calibration of the temperature dependence of the sensitivity of the microwave system revealed that the amplitude of the transmission signal increased by a factor of -4 between 4.2 and 300 K. In this particular crystal orientation the longitudinal sound wave is coupled to the rfmagnetization via the magnetoelastic coupling. The modest residual resistivity ratio (15) of our sample ruled out geometric resonance absorptions. None were observed.