This proposal requests funds for continued support of investigations into the magnetic and electrical properties of uncompensated magnetic garnet films. It has been observed that thin films of the magnetic garnets, of which the prototype is yttrium iron garnet can be grown in which the divalent calcium ion will substitute for the trivalent yttrium ion forming a charge uncompensated material. Preliminary measurements show encouraging potential for the development of new magnetic semiconductor materials. In particular, at low temperatures a photo-electrical effect has been observed that enhances the conductivity by six orders of magnitude and a photomemory effect is also observed. The magnetic properties are also unusual in that a strong decrease of the magnetic moment is observed at temperatures below 150 K. At this same temperature the ferrromagnetic resonance indicates a significant increase in the internal fields of the materials. A model has been proposed in which the population of the quadruvalent iron ion varies exponentially with temperature having a characteristic energy of 150 K. The second area involves an investigation into the magneto- optical properties of bismuth-thullium: yttrium iron garnet. The thullium ion with it's large angular orbital momentum produces a significant shift from the g=2 resonance condition normally observed in the yttrium iron garnet like materials. It is proposed that trivalent iron ion might be an excellent probe to further investigate the role of the angular momentum of the higher order states of iron to investigate the origin of the Faraday rotation observed in bismuth magnetic garnets.
