STUDY OF FERRIMAGNETIC CRYSTALS BY PARALLEL PUMPING.
AIR FORCE CAMBRIDGE RESEARCH LABS L G HANSCOM FIELD MASS
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A study of single-crystal ferrimagnetic crystals at microwave frequencies was conducted. The parallelpumping technique was used to experimentally measure spin-wave linewidth, magnetoelastic coupling constants, energy exchange constants, and phonon linewidths. The experiments were carried out at 300K, 194K, 77K, and 4.2K at X- and K-band frequencies. Four samples of pure, single-crystal yttrium iron garnet one disk, and three spheres were extensively investigated. Conditions for optimum detection sensitivity of spin-wave instability measurement are given and discussed. The theory of parallel pumping is explained and worked out in detail. Expressions are obtained for spin-wave and phonon linewidths, magnetoelastic constants and exchange constants in terms of experimentally measured quantities. A literature search was made for publications dealing with parallel-pumping phenomena. These articles over 75 are abstracted for their contents relative to this investigation. Author