Accession Number : AD0702415

Title :   RELAXATION IN SEVERAL MAGNETIC MATERIALS.

Descriptive Note : Technical rept.,

Corporate Author : HARVARD UNIV CAMBRIDGE MASS DIV OF ENGINEERING AND APPLIED PHYSICS

Personal Author(s) : Bartkowski,Richard R.

Report Date : NOV 1969

Pagination or Media Count : 84

Abstract : Investigations in several interesting materials were conducted over a wide temperature range with the use of the ferromagnetic resonance and parallel pump techniques. The materials investigated are CdCr2Se4, EuS, and NiFe2O4. The first two are ferromagnetic, NiFe2O4 is ferromagnetic and all are insulators. CdCr2Se4 was investigated from 4 degrees K to the Curie temperature by the parallel pump instability. Ferromagnetic resonance data extends to room temperature. The linewidth as measured by both techniques shows an abrupt rise in the vicinity of the transition temperature. EuS was investigated by the parallel pump instability in the low temperature region. Here the dominant source of relaxation is the three-magnon process. These data are compared with the linewidths calculated for this process. NiFe2O4 was investigated from 2 degrees K to room temperature by the parallel pump technique. Comparison of this with the available ferromagnetic resonance data shows that the latter is dominated by two-magnon processes. The parallel pump linewidth appeared to be that of a slowly relaxing impurity. (Author)

Descriptors :   (*MAGNETIC MATERIALS, *MAGNETIC RESONANCE), CADMIUM COMPOUNDS, CHROMIUM COMPOUNDS, EUROPIUM COMPOUNDS, IRON COMPOUNDS, NICKEL COMPOUNDS, OXIDES, SELENIDES, SULFIDES, PHONONS, IMPURITIES, CRYOGENICS

Subject Categories : Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE