High-Pressure Investigations of Correlated-Electron Phenomena

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" High-Pressure Investigations of Correlated-Electron Phenomena "
Wolowiec, Christian Maple, M. Brian

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	899076
Doc. No	:	TL32s9x56t
Main Entry	:	Kou, Yubo
Title & Author	:	High-Pressure Investigations of Correlated-Electron Phenomena\ Wolowiec, ChristianMaple, M. Brian
Date	:	2017
student score	:	2017
Abstract	:	This dissertation includes a discussion of the results of measurements of electrical resistivity for materials under applied pressure extending over a range in pressures from 0 to 27 GPa and temperatures from 1 to 300 K. The primary effect of applying pressure to a solid is to reduce the interatomic distance and to increase the overlap of the electronic orbitals. The secondary effects of applying pressure to a solid include the delocalization of electrons and a broadening of the energy bands. In addition, the application of pressure can induce a variety of transitions, both electronic and structural. Some of the phenomena observed during the pressure experiments reported in this dissertation include the pressure-induced enhancement of the superconducting transition temperature in a recently discovered class of bismuth-sulfide layered superconductors, the anomalous “dome-like” behavior in the pressure dependence of the Néel temperature in the first-known synthesis of an itinerant antiferromagnetic metal with non-magnetic constituents TiAu, and the evolution of the pressure-induced first-order transition to antiferromagnetism in the Fe-substituted heavy fermion compound URu2Si2. These and other results including a semiconductor-metal transition in the normal state of one of the bismuth-sulfide layered superconducting compounds are a consequence of the electronic and structural transitions that can occur as a result of the application of pressure. The theoretical context for the experimental results includes a discussion of the effect of pressure on the relevant parameters in condensed matter theory including the density of states, the exchange interaction in both the localized and itinerant models of magnetism, and the electron-phonon coupling parameter, among others. In particular, the pressure dependence of the magnetic ordering temperature and the superconducting transition temperature in various materials can be explained in terms of how the few parameters listed above respond to pressure.
Added Entry	:	Wolowiec, Christian
Added Entry	:	UC San Diego