THEORY OF FERRIMAGNETISM IN INSULATORS.
BATTELLE MEMORIAL INST COLUMBUS OHIO COLUMBUS LABS
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The purposes of this investigation have been to develop, with as much rigor as possible, improved spin-wave theories, to use the theories developed to obtain interpretive formulas for the transition temperature, dispersion curves, and the thermodynamic properties of magnetic insulators, and, somewhat more specialized, to explain the anomalous magnitude of the low-temperature heat capacity of a large number of ferrites, typified by magnetite. There have been three principal accomplishments 1 A theory of spin-waves in ferrites of arbitrary structure and general exchange constants has been derived 2 A theory of the effect of statistical interference among spin-waves, resulting from the operation of the Pauli principle, has been developed for a system of spins of magnitude one-half with antiferromagnetic exchange and 3 A theory of the possible influence of magnetostatic modes of oscillation of the spin system on the heat capacity of ferrites was derived. In addition to these results, research has been carried out and is continuing on the application of functional techniques to the derivation of more reliable spin-wave theories, and on the application of the theory 1, above, to the metamagnetic transition metal chlorides.
- Electricity and Magnetism
- Solid State Physics