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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Growth and Characterization of Sr2RuO4 and Sr2RhO4 / Growth and Characterization of Strontium Ruthenate (214) and Strontium Rhodate (214)

Mortimer, Kevin January 2014 (has links)
With reference to some figures reproduced in this thesis: "Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modified, adapted, performed, displayed, published, or sold in whole or part, without prior written permission from the American Physical Society." / We report on the growth and characterization of strontium ruthenate (214) (Sr2RuO4) and strontium rhodate (214) (Sr2RhO4) in efforts to test their agreement with Landau-Fermi liquid theory using optical measurements. We begin by reviewing the theory of Landau-Fermi liquids and the frequency and temperature dependent conductivities. We review existing work on both Sr2RuO4 and Sr2RhO4 including evidence of agreement with Landau-Fermi liquid theory. We also describe optical floating zone crystal growth and the exact procedures we used to prepare samples of both Sr2RuO4 and Sr2RhO4 via optical floating zone. The resulting Sr2RuO4 crystals were characterized using AC susceptibility measurements and Sr2RhO4 by powder diffraction, single crystal diffraction, and SQUID magnetization measurements. Finally, early optical reflectivity measurements at low temperatures are presented. / Thesis / Master of Science (MSc) / Crystals of Sr2RuO4 and Sr2Rho4 were grown by the author in an effort to study changes of their resistivity with varying temperature and frequency at low temperatures. The crystals were characterized using a variety of x-ray and other techniques, so as to measure their purity. Past work on these materials is discussed and analyzed. Preliminary measurements of the resistivity are presented.
2

Studies of the Low Temperature Behaviour of CoNb2O6

Munsie, Timothy J.S. 04 1900 (has links)
<p>This thesis is the result of several experiments designed to probe the low temperature physics underlying the 1D-Ising-like behaviour of chains of spins in the structure of Cobalt Niobate, CoNb2O6. A collection of prior work has been done by several groups prior to this, focusing on mapping the phase diagram above 0.5K. Interest in this material was renewed recently based upon theoretical work and experimental confirmation of the unique structure of the spins in the system. The bulk of this work was done at temperatures below the previously investigated range to probe the unique properties of this system.</p> <p>The material was grown at McMaster University using the optical floating zone technique from oxide powders. The crystal was examined and oriented using single crystal and Laue diffraction and was cut for use in further experiments. Squid magnetometry was used to confirm the material properties and phase transition temperatures, and was compared to literature values.</p> <p>Heat capacity measurements were performed locally down to 2K, and by collaborators at Waterloo in the range from 330mK to 1K. The heat capacity measurement confirmed the 2.9K transition and explored the relaxation time of the material. Cobalt niobate was found to have an exceptionally long relaxation time at low temperatures indicating strong spin-spin interactions. A sharp transition with zero applied field was found to become a broad, smooth feature at 2.9K when a small field was applied.</p> <p>We performed muSR measurements in zero, longitudinal and transverse field. The muSR results confirmed the long relaxation time found by the heat capacity measurements, which may reflect the coupling of the spin system to the lattice. Additionally, the material was never seen to statically order in zero or longitudinal field down to 700mK and up to 1T. The material was found to behave dynamically throughout all the field ranges.</p> / Master of Science (MSc)

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