Effect of the large magnetostriction of Terfenol-D on microwave transmission and reflection

The purpose of this dissertation is to study certain physical properties of Terfenol-D, a magnetic material which is extremely magnetostrictive. Of particular interest is the magnetoelastic behavior of Terfenol-D when interacting with the microwave radiation in the presence of a static magnetic field. A microwave transmission spectrometer was used to measure transmission and I modified the spectrometer to perform reflection measurements. Experiments were done over a small temperature interval near room temperature using static magnetic fields from 0 kOe to 13 kOe and with microwaves of frequency 16.95 GHz. The results of this study followed from observing at what magnetic field ferromagnetic resonance (FMR) occurs. The enormous anisotropy of Terfenol-D should shift the field for ferromagnetic resonance; the experimental results confirm this effect and give an experimental value for the anisotropy constant of K1 = (−2.00 ± 0.025) x 106 erg/cm3 at room temperature. Observation of the microwave transmission through Terfenol-D should confirm the predicted role magnetostriction plays in its response to microwaves.