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Ferromagnetism at Very High Frequencies. IV. Temperature Dependence of the Magnetic Spectrum of a Ferrite

1952; American Institute of Physics; Volume: 88; Issue: 4 Linguagem: Inglês

10.1103/physrev.88.909

1536-6065

George T. Rado, R.W. Wright, W. H. Emerson, A. Terris,

Electromagnetic wave absorption materials

The magnetic spectrum of a sintered ferrite, previously studied by the authors at room temperature and found to contain an rf resonance, attributed to domain wall displacements, and a microwave resonance, attributed to domain rotations, has now been observed at 77\ifmmode^\circ\else\textdegree\fi{}K, 195\ifmmode^\circ\else\textdegree\fi{}K, and 411\ifmmode^\circ\else\textdegree\fi{}K. By using single-domain particles of this material embedded in wax, the rotational resonance was observed separately. The principal aspect of the experimental results is the fact that with increasing temperature the resonance frequencies decrease, the fractional change being about the same in all three cases and exceeding that of the saturation magnetization. A semiquantitative theoretical interpretation of this fact is given. Auxiliary experiments, performed as an aid in interpreting the magnetic spectrum, include measurements of the spectroscopic splitting factor $g$ at various temperatures. The deviation of the apparent $g$ factor values from $g=2$, as well as their temperature dependence, was found to decrease with increasing resonance field, i.e., increasing resonance frequency.