Type of Document Dissertation Author Conner, Benjamin Scott Author's Email Address email@example.com URN etd-06302011-093014 Title Single crystal growth and magnetic and thermal properties of Pb2V3O9 Degree Doctor of Philosophy Department Physics, Department of Advisory Committee
Advisor Name Title Luis Balicas Committee Co-Chair Vladimir Dobrosavljevic Committee Co-Chair Grigory Rogachev Committee Member James Brooks Committee Member Pedro Schlottmann Committee Member Naresh Dalal University Representative Keywords
- floating zone crystal growth
- field induced magnetic ordering
Date of Defense 2011-06-24 Availability unrestricted AbstractElectrical insulators provide the opportunity to study the effects of magnetic interactions in the absence of conduction electrons. Since about ten years ago, experiments on a few insulating dimerized antiferromagnets have shown a low temperature, concave-down feature in magnetic susceptibility under magnetic fields larger than a critical value that was difficult to explain. Also, features in heat capacity remnant of the lambda anomaly associated with the superfluid transition in liquid 4He were observed after an applied magnetic field was increased beyond the same critical value. These observations are associated with long-range magnetic ordering that has been described as a Bose-Einstein condensation (BEC) of the integer spin excitations, the magnons. Although magnons cannot strictly form a BEC, the BEC description has been qualitatively successful in describing some of the measured quantities of the small number of insulating antiferromagnets that exhibit a field induced low temperature, concave-down susceptibility. Pb2V3O9 is one system that exhibits this field induced low temperature, concave-down magnetic susceptibility and has been ascribed this BEC description. This thesis outlines the following:
1. The floating zone crystal growth of single crystals of Pb$_2$V$_3$O$_9$ is presented. This thesis outlines what is possibly the first successful effort to grow single crystals of Pb$_2$V$_3$O$_9$ via the floating zone method.
2. Measurements of the physical properties of Pb$_2$V$_3$O$_9$ with applied magnetic fields as large as 45 T, specifically those properties associated with the field-induced long range ordered phase, are presented.
3. The observation of glassy magnetic behavior in Pb$_2$V$_3$O$_9$ observed for the first time in off-stoichiometric samples is presented. This glassy magnetic behavior is found to be in competition with the field-induced long range ordered phase.
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