MICROWAVE PROPERTIES OF PARTIALLY MAGNETIZED FERRITES.
Semi-annual technical rept. 5 Jul 67-5 Jan 68,
RAYTHEON CO WALTHAM MA RESEARCH DIV
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Measurements of mu and kappa as a function of gamma 4 pi M sub somega and gamma 4 pi Momega have been made on two common, commercially available, polycrystalline ferrites, G-113, a yttrium iron garnet, and TT1-390, a magnesium manganese spinel. The corresponding absorption components of the tensor permeability have also been measured on G-113 at room temperature. mu double prime-kappa double prime shows a peak at negative fields. A system to measure magnetic loss in the demagnetized state on very low loss materials having mu double prime in the 10 to the -4th power or 10 to the -5th power region has been built and several materials have been measured. Measurements of the spin wave instability threshold, hcrit, have been made on partially magnetized thin disks. An attempt to understand the dependence of hcrit as a function of orientation of the disks, the rf magnetic field, and the dc magnetization in terms of the domain structure and the behavior of hcrit in magnetically saturated disks is being made. Author
- Electricity and Magnetism