Accession Number : AD0615370

Title :   MAGNETIC ANNEAL EFFECTS IN SOME GARNETS,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE LAB FOR INSULATION RESEARCH

Personal Author(s) : HUNT,Robert P.

Report Date : APR 1965

Pagination or Media Count : 46

Abstract : Many properties of polycrystalline and reduced single crystal yttrium iron garnet (YIG) have been attributed to the presence of Fe(2+) ions which provide mobile electrons that can diffuse locally through the lattice. This electron-diffusion process was studied by means of several low-temperature torque experiments on silicondoped YIG of the form Y3Fe(5-delta)Si delta with 0 < delta < 0.18. Silicon-doped YIG, which contains mobile electrons, shows an induced anisotropy proportional to the doping when magnetically annealed at low temperatures. The kinetics and temperature dependence of this anisotropy were investigated. The garnet also demonstrates a constant high field component of rotational hystersis which is both temperature and frequency dependent. The intrinsic, unannealed anisotropy behaves in a novel way. At room temperature it coincides with that of normal YIG, but between 150 and 300K (K sub 1) increases above that of pure YIG. Below about 150K the curves develop asymmetry and are no longer cubic. At 4.2K the easy axis has shifted to the (100) direction in the case of 3% doping. (Author)

Descriptors :   (*GARNET, MAGNETIC PROPERTIES), (*FERROMAGNETIC MATERIALS, ANISOTROPY), YTTRIUM COMPOUNDS, IRON COMPOUNDS, IMPURITIES, SILICON, DIFFUSION, SINGLE CRYSTALS, CRYSTALS, LOW TEMPERATURE, HEAT TREATMENT, KINETICS, HYSTERESIS, LUTETIUM COMPOUNDS, HEAT OF ACTIVATION, RELAXATION TIME

Distribution Statement : APPROVED FOR PUBLIC RELEASE