Description
- Abstract:
- Materials with strongly interacting electrons exhibit a wide variety of unconventional ordering phenomena that are both fundamentally rich and promising for many potential technological applications. These phases often involve coupling between spin, charge, orbital, and lattice degrees of freedom, precisely tuned by a hierarchy of energy scales. They may also involve more subtle degrees of freedom that may be elusive to many common experimental probes. In this thesis, I discuss a series of resonant elastic and inelastic x-ray scattering experiments (REXS/RIXS) on complex magnetic materials to uncover the microscopic mechanisms behind the novel magnetic phenomena observed in these materials. NiRh2O4 is a S=1 frustrated diamond lattice antiferromagnet that may be in proximity to a quantum critical point. I carried out RIXS measurements to unravel the spin-orbital-lattice entangled ground state in NiRh2O4. CoNb3S6 is an intercalated transition metal dichalcogenide (iTMD) exhibiting a giant anomalous Hall effect (AHE) that cannot be explained by its putative collinear antiferromagnetic order. Using REXS, I discovered a long-wavelength modulation of the magnetic structure that gives rise to a novel striped pattern in the scalar spin chirality. The properties of iTMDs are highly sensitive to the precise stoichiometry of intercalated 3d ions. I carried out comprehensive magnetic and structural characterization on CoNb3S6 and the related material NiNb3S6 with varying Co and Ni stoichiometry to understand the dependence of the magnetic properties on sample composition. NiGa2S4 is a nearly ideal S=1 triangular lattice magnet which shows no long range magnetic order and exhibits a variety of unconventional magnetic properties. I carried out REXS measurements to probe the magnetic correlations within a small sample volume to disentangle structural and magnetic disorder. I find a correlation length that is longer than that found in previous measurements, as well as a temperature-induced shift in the magnetic wavevector. Using RIXS, I ruled out the previously reported negative charge transfer ground state and instead found a mixed valence state.
- Notes:
- Thesis (Ph. D.)--Brown University, 2024
Citation
Zager, Benjamin,
"Uncovering Novel Phases in Complex Magnetic Materials Using Resonant X-ray Scattering"
(2024).
Physics Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://repository.library.brown.edu/studio/item/bdr:hqzv9gea/
