Publication Date

1998

Document Type

Dissertation/Thesis

First Advisor

Brown, Dennis Eugene

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Physics

LCSH

Rare earth metal compounds--Magnetic properties; Mössbauer effect

Abstract

The Mössbauer effect is a phenomenon that makes it possible to study local magnetic and electric interactions. General concepts along with computational methods are introduced in the theoretical part of this thesis. Mössbauer studies have been conducted on ^57Fe doped colossal magnetoresistive rare-earth transition metal oxides. Temperature dependent Mössbauer effect, magnetization and resistivity measurements have been made for La[sub 1-x]Sr[sub x]Mn[sub 0.9]Fe[sub .1]O[sub 3] (x=0,0.1,0.2,0.3). Various techniques of synthesis (air, Ar, quenching, slow cooling) were used to create compounds that are virtually free of defects. The 57Fe was shown to have a valence state of 3+ from the Mössbauer effect measurements. As x increases, the crystal structure changes from monoclinic to orthorhombic to rhombohedral, and the transport properties change from antiferromagnetic-semiconductor to ferromagnetic-semiconductor to ferromagnetic-colossal magnetoresistive metal. The Mössbauer effect shows broader distributions of magnetic fields below the magnetic ordering temperature as x is increased. The experimental results are discussed in terms of local structure and time-dependent magnetic exchange interactions.

Comments

Includes bibliographical references (pages [61]-62)

Extent

xvii, 62 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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