Within in this work, I present the successful synthesis of Ba6Yb2Ti4O17 in a powder
form. To the best of my knowledge, this is the first instance in which this
has been achieved. I also show that single crystal synthesis experiments using
the floating zone synthesis (FZS) technique have yet to produce single crystals.
The magnetic characterization of Ba6Yb2Ti4O17 powder is also presented. DC
susceptibility measurements reveal no spin freezing or ordering down to 0.5K and
inverse susceptibility shows antiferromagnetic coupling between spins. A cold neutron
scattering experiment was performed at low temperatures with and without
an applied magnetic field on Ba6Yb2Ti4O17 powder. This experiment shows the
possibility of spinon-like excitations with a band width of approximately 0.3meV,
but this is inconclusive due to the signal to noise ratio. The powder averaged
g-tensor for Ba6Yb2Ti4O17 was also experimentally estimated to be approximately
2.4. Further work required to complete this study is also discussed.
Synthesis of phase pure ErMgGaO4 has yet to be reported in the literature.
Here, I show that small amounts of phase pure polycrystalline ErMgGaO4 can
be produced using the FZS technique. Through using FZS, 0.85g of phase pure
ErMgGaO4 powder was produced and supplemented using 1.26g of ErMgGaO4
powder containing approximately 1% Er3Ga5O12 magnetic impurity. To estimate
the effect of this magnetic impurity on the magnetic signatures exhibited
by ErMgGaO4, DC susceptibility measurements were performed between 0.5K
and 50K. The magnetic impurity in such small quantity was shown to have negligible
effect on the bulk ErMgGaO4 magnetic features. Cold neutron scattering
conducted on this material revealed a spinon excitation continuum similar to the
one observed in YbMgGaO4.[1] Also present at low temperatures was a diffuse
elastic magnetic feature that was used to estimate an order parameter for the material.
Analysis of this diffuse feature also revealed a Warren line shape, indicative
of two dimensional correlations within the Er3+ triangular planes. Analysis of the
spinon excitation continuum revealed a gapless spinon continuum overall. Results
presented for both Ba6Yb2Ti4O17 and ErMgGaO4 will be discussed and compared
to neutron scattering experiments performed on YbMgGaO4 / Thesis / Master of Science (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/26083 |
| Date | January 2020 |
| Creators | Cronkwright, Zachary W. |
| Contributors | Gaulin, Bruce, Physics and Astronomy |
| Source Sets | McMaster University |
| Detected Language | English |
| Type | Thesis |
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