Accession Number : AD0638302

Title :   INDETERMINACY OF MOLECULAR FIELD COEFFICIENTS IN FERRIMAGNETS USING THE ANALYTICAL METHOD.

Descriptive Note : Physical sciences research papers.

Corporate Author : AIR FORCE CAMBRIDGE RESEARCH LABS L G HANSCOM FIELD MASS

Personal Author(s) : Gianino,Peter D. ; Grossbard,Neil

Report Date : MAY 1966

Pagination or Media Count : 35

Abstract : It was demonstrated that the analytical method proposed by Rado and Folen to calculate molecular field coefficients in ferrimagnets does not yield unique values of alpha and beta for YIG and lithium ferrite. Instead, only one of many possible pairs of (alpha, beta) values from a linearly related set are determined. The magnitudes of the internal magnetic fields, total magnetic moment and the two sublattice magnetic moments, computed from any one of these possible coefficients, remain relatively unchanged even though the (alpha, beta) and n are extremely sensitive both to input parameters and to the number of experimental data points utilized. From within the framework of the theory itself it is shown how it is possible for this manifold of (alpha, beta) pairs to exist, how they can be related in a linear manner, and how an analytic expression for this dependency can be derived, utilizing low temperature information. A procedure for testing whether the coefficients for other ferrimagnets can be determined uniquely is discussed. Best values of (alpha, beta) are obtained by minimizing a least squares percentage error. These values not only fall along a straight line but are in good agreement with those generated in the usual application of the analytical method, thus further strengthening our contention. The possibility of using Rado's linearity test as a criterion on which to judge the appropriateness of the selected value of the Curie point is shown to be invalid. Results for the various magnetic moments and internal fields under varying input conditions are given for both YIG and lithium ferrite. (Author)

Descriptors :   (*FERROMAGNETIC MATERIALS, *FIELD THEORY), YTTRIUM COMPOUNDS, IRON COMPOUNDS, GARNET, LITHIUM COMPOUNDS, FERRITES, MAGNETIC PROPERTIES, MAGNETIC PROPERTIES, THEORY

Subject Categories : Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE