Accession Number : ADA300544

Title :   Uncompensated Garnets: A Magnetic Semiconductor.

Descriptive Note : Rept. for 1 Mar 91-31 Dec 94,

Corporate Author : OHIO STATE UNIV COLUMBUS DEPT OF PHYSICS

Personal Author(s) : Wigen, Philip E.

PDF Url : ADA300544

Report Date : 09 MAY 1995

Pagination or Media Count : 36

Abstract : Yttrium iron garnet (YIG) is a ferrimagnetic oxide, Y3Fe5O12 and a good insulator. When five to ten percent of the Y(3+) is replaced by Ca(2+), an uncompensated state exists. The resulting material has perturbed magnetic properties, semiconducting electrical properties with activation energies from 0.2 to 0.4 eV and resistivities as low as 300 ohm cm at room temperature, and modified optical properties. In the past year the conductivity studies have concentrated on the evolution of a high conduction state in samples that have been annealed in a reducing atmosphere. The reduction process introduces oxygen vacancies which should compensate the hole introduced by Ca(2+). The annealing is also observed to modify significantly the effective exchange constant of the material and the optical activity. These measurements are summarized in this report.

Descriptors :   *MAGNETIC PROPERTIES, *SEMICONDUCTORS, *GARNET, *YTTRIUM IRON GARNET, CALCIUM, CATIONS, OPTICAL PROPERTIES, ANNEALING, CONDUCTIVITY, INSULATION, HOLES(ELECTRON DEFICIENCIES), ELECTRICAL PROPERTIES, ROOM TEMPERATURE, REDUCTION, OXYGEN, OXIDES, EVOLUTION(GENERAL), PERTURBATIONS, ELECTRICAL RESISTANCE, COMPENSATION, EXCHANGE, MAGNETIC MATERIALS, ACTIVATION ENERGY, FERRIMAGNETISM.

Subject Categories : Geology, Geochemistry and Mineralogy
      Inorganic Chemistry
      Electrical and Electronic Equipment
      Electricity and Magnetism
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE