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Superconducting, Structural, and Magnetic Properties of Lithium and Lithium-Rich Compounds

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Superconducting, Structural, and Magnetic Properties of Lithium and Lithium-Rich Compounds SUPERCONDUCTING, STRUCTURAL, AND MAGNETIC PROPERTIES OF LITHIUM AND LITHIUM-RICH COMPOUNDS by Anne Marie Schaeffer Richards A dissertation submitted to the faculty of The University of Utah in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Physics Department of Physics and Astronomy The University of Utah May 2016 Copyright © Anne Marie Schaeffer Richards 2016 All Rights Reserved The University of Utah Graduate School STATEMENT OF DISSERTATION APPROVAL The dissertation of Anne Marie Schaeffer Richards has been approved by the following supervisory committee members: Stephan LeBohec Chair 11/24/2015 Date Approved Jordan Gerton Member 11/24/2015 Date Approved Eugene Mishchenko Member 11/24/2015 Date Approved Lowell Miyagi Member 11/24/2015 Date Approved Clayton Williams Member 11/24/2015 Date Approved and by Carleton DeTar Chair/Dean of the Department/College/School o f _____________Physics and Astronomy and by David B. Kieda, Dean of The Graduate School. ABSTRACT Lithium is generally considered to be a simple metal, given its simple electronic structure with one valence electron. It is considered to follow a nearly free electron model and have a nearly spherical Fermi surface. However, away from ambient conditions, the behavior of lithium becomes much less simple. Under high pressures, lithium undergoes a series of sym­ metry breaking phase transitions, even a metal to insulator transition; at low temperatures, lithium also undergoes a temperature-driven martensitic transformation. In this work, these deviations from simple models in lithium are investigated, both at ambient pressure and under high pressures, from the relative high temperature phenomenon of melting, to low temperature measurements of superconductivity. CONTENTS A B S T R A C T ................................................................................................................................ iii L IST O F F IG U R E S ................................................................................................................ vii L IST O F T A B L E S .................................................................................................................... xvi A C K N O W L E D G M E N T S .................................................................................................... xvii C H A P T E R S 1......I N T R O D U C T I O N ........................................................................................................... 1 1 .1 Alkali M etals.................................................................................................................. 1 1.2 L ithium ........................................................................................................................... 2 1.3 Quantum Solids.............................................................................................................. 2 1.3.1 Nearly Free Electron M o d e l............................................................................. 3 1.4 Extreme Conditions....................................................................................................... 4 1.4.1 Pressure.................................................................................................................. 4 1.4.2 Tem perature......................................................................................................... 5 1.5 High Pressure M elting.................................................................................................. 5 1.5.1 Quantum M eltin g............................................................................................... 7 1.6 Superconductivity......................................................................................................... 8 1.7 Crystal Structure........................................................................................................... 10 1.8 Fermi Surface ................................................................................................................ 14 2. E X P E R IM E N T A L T E C H N I Q U E S ........................................................................ 18 2.1 Pressure ............................................................................................................................ 18 2 .1 .1 Diamond Anvil Cell ........................................................................................... 18 2.1.2 Paris-Edinburgh Press......................................................................................... 21 2.1.3 Pressure Measurement ...................................................................................... 22 2.1.3.1 Ruby Fluorescence .................................................................................... 22 2.1.3.2 Equation of State ...................................................................................... 26 2.2 Temperature .................................................................................................................. 27 2.2.1 Low Temperature ................................................................................................ 27 2.2.1.1 Cryostat ....................................................................................................... 27 2.2.2 High Temperature ................................................................................................ 28 2.2.2.1 Laser H eating............................................................................................. 29 2.2.2.2 Resistive H ea tin g ...................................................................................... 29 2.3 High Pressure Resistance Measurements................................................................. 30 2.3.1 Resistance for Detecting Melting of Metals ................................................. 36 2.3.2 Resistance for Detecting Superconductivity................................................. 38 2.4 AC Magnetic Susceptibility ......................................................................................... 40 2.5 de Haas van Alphen Effect ........................................................................................ ...45 2.5.1 Torque Magnetometry........................................................................................ ...45 2.6 Diffraction..........................................................................................................................46 2.6.1 X-Ray D iffraction...................................................................................................46 2.6.2 Neutron Diffraction............................................................................................. ...50 2.6.3 Analysis.................................................................................................................. ...51 3. H IG H P R E S S U R E M E L T IN G O F L I T H I U M ....................................................54 3.1 Abstract ......................................................................................................................... ...54 3.2 Introduction .................................................................................................................. ...55 3.3 Methods ......................................................................................................................... ...56 3.4 Experim ent.................................................................................................................... ...59 3.5 Results .................................................................................................................................61 3.6 Conclusion ..........................................................................................................................63 3.7 Notes on Laser H eating............................................................................................... ...63 4. TWIN SAMPLE CHAMBER FOR SIMULTANEOUS ELECTRONIC TRANSPORT MEASUREMENT IN A DIAMOND ANVIL CELL ... 65 4.1 Abstract ......................................................................................................................... ...65 4.2 Introduction .................................................................................................................. ...6 6 4.3 Experimental Setup ..........................................................................................................67 4.4 Conclusion ..........................................................................................................................71 4.5 Notes ................................................................................................................................ ...72 5. HIGH-PRESSURE SUPERCONDUCTING PHASE DIAGRAM OF 6 LI: IS O T O P E E F F E C T S IN D E N S E L IT H IU M .............................................73 5.1 Abstract ......................................................................................................................... ...73 5.2 Introduction .................................................................................................................. ...74 5.3 Experiment and Results ............................................................................................. ...75 5.4 D iscussion..........................................................................................................................81 5.5 Notes on Pressure Distribution.....................................................................................84 6 . NEW BOUNDARIES FOR MARTENSITIC
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