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http://hdl.handle.net/11375/27228
Title: | μSR and AC Susceptibility as a probe of Frustrated Pyrochlore Magnets and Type-1 Superconductivity |
Authors: | Beare, James Walter |
Advisor: | Luke, Graeme |
Department: | Physics and Astronomy |
Keywords: | Frustrated Magnetism;muSR;Superconductivity |
Publication Date: | 2021 |
Abstract: | In this thesis, we use Muon Spin Rotation, Relaxation, and Resonance (μSR) as a probe for three frustrated pyrochlore systems; Gd2ScNbO7 (GSNO), Nd2ScNbO7 (NSNO) and Sm2Ti2O7 (STO), as well as the type-I superconductor BeAu. We grew all of the pyrochlore samples at McMaster using the Optical Floating Zone method. We make use of Direct Current (DC) and Alternating Current (AC) susceptibility, powder x-ray diffraction and Laue x-ray diffraction to characterize our samples. We make use of AC susceptibility measurements to explore the dynamics of the classical spin-ice Dy2Ti2O7 (DTO) and find that the system acts as a supercooled magnetic liquid, analogous to glassforming dielectric liquids. We find GSNO is a dense spin-glass based on our μSR and AC susceptibility measurements. NSNO is a moment fragmentation candidate where spin-ice, as well as all-in all-out magnetic ordering, are observed simultaneously. Our μSR measurements on this material show a strong similarity to another moment fragmentation candidate, Nd2Zr2O7, suggesting NSNO may be in a similar state. STO is a closely related compound that fully orders into a magnetic state which we study using μSR. We find subtle evidence of this magnetic transition along with persistent spin dynamics which we suggest has a common, but as of yet unexplained, origin as other frustrated pyrochlores measured in μSR. Finally, we use μSR to measure the temperature dependence of the critical field in the type-I superconductor BeAu. Using an ellipsoid of BeAu and a pressure cell, we study the magnetic properties of the sample under pressure. |
URI: | http://hdl.handle.net/11375/27228 |
Appears in Collections: | Open Access Dissertations and Theses |
Files in This Item:
File | Description | Size | Format | |
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Beare_James_W_2021Nov_PhD.pdf | 28.02 MB | Adobe PDF | View/Open | |
Reuse_Mauws_2021.pdf | 193.44 kB | Adobe PDF | View/Open | |
Reuse_Scheie_20201.pdf | 52.18 kB | Adobe PDF | View/Open | |
Rights_21_SEP_Xu_2019.pdf | 51.36 kB | Adobe PDF | View/Open | |
Rights_AnnualReview_Alannah.pdf | 181.79 kB | Adobe PDF | View/Open |
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