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. / Thesis / Candidate in Philosophy / 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.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/27228 |
| Date | January 2021 |
| Creators | Beare, James Walter |
| Contributors | Luke, Graeme, Physics and Astronomy |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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