Soma Khanra

Date of Graduation

Fall 2012

Degree

Master of Science in Materials Science

Department

Physics, Astronomy, and Materials Science

Committee Chair

Pawan Kahol

Abstract

Yttrium iron garnet (YIG) is a synthetic garnet and ferrimagnetic with chemical formula Y3Fe5O12. In YIG, five iron (III) ions occupy two octahedral and three tetrahedral sites, with the yttrium (III) ions coordinated by eight oxygen ions in an irregular cube. The iron ions in the two coordination sites exhibit different spins, resulting in ferrimagnetic behavior. YIG is used in microwave, optical, and magneto-optical applications, e.g. microwave YIG filters, solid-state lasers, and data storage. In view of these interesting properties and important applications, YIG and Mo doped YIG have been synthesized systematically using solid state reaction method. The phase purity and structural details were confirmed using X-ray diffraction, scanning electron microscopy, and Raman spectroscopy. XRD study shows that all samples exhibit a cubic structure with a lattice constant of about 12 angstrom. Room temperature dielectric measurements indicate that the YIG shows the usual dielectric dispersion. Molybdenum(x=0.02, 0.05, 0.1) has been used to dope and thereby change the magnetic and electrical properties of yttrium iron garnet. Electrical and optical data show that the electrical conductivity increases and the band gap decreases with Mo doping. It is found that band gap engineering is possible through Mo doping. Magnetization data shows that saturation magnetization increases at low values and then decreases with additional Mo doping. It is found that the coercive field of Mo doped YIG can be tuned through Mo doping. All the results indicate that Mo-doping may provide suitable YIG spintronic materials for future spin electronic devices.

Keywords

Y[3]Fe[5]O[12], spintronics magnetic semiconductors, ferromagnetism, ferrimagnetism

Subject Categories

Materials Science and Engineering

Copyright

© Soma Khanra

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