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Ferrimagnetic Relaxation Measurements and Microwave Circuit Properties of Ferrite Ellipsoids
STANFORD UNIV CA STANFORD United States
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The paper describes the results of an experimental investigation of relaxation processes in microwave ferrites. A new experimental procedure was developed in which the contribution of the uniform precessional mode to the relaxation may be separated from that of the other spin modes by controlling the interaction between the ferrite sample and its microwave environment. To characterize this interaction in detail, scattering matrix and lumped-element equivalent circuit representations were developed for a section of uniform waveguide containing a small ferrite ellipsoid. The circuit representation was then used to discuss radiation damping in a variety of microwave structures. In contrast to previous theories, the results are valid even when the interaction is large, provided that the sample is not too close to a waveguide wall. This wall effect, which takes the form of a shift, broadening and distortion of the resonance line, is discussed in some detail. Transient solutions were obtained for the rate equations which describe the deviation of the z-component of magnetization from its equilibrium value, in the presence of appreciable radiation damping.
APPROVED FOR PUBLIC RELEASE