Description
- Abstract:
- A wide array of experimental probes of matter have been developed in order to gain a more accurate and complete understanding of the microscopic nature of emergent quantum phenomena---a cornerstone of condensed matter research. In the study of a single system or material, multiple probes are employed in order to build a complete picture, since each probe naturally faces limitations in the information accessible to it. As our understanding of quantum phenomena expands, so must the range of tools used to study them, which motivates the development of novel quantum probes of matter. This thesis focuses on the experimental implementation of novel quantum probes that aim to expand our understanding of magnetic fluctuations in strongly correlated systems. Specifically, this work focuses on the experimental implementation of two novel quantum sensing techniques: a quantum mechanical magnetic camera that utilizes noise spectroscopy of magnetic tunneling junctions (MTJ) to detect magnetic fluctuations in materials with a high level of spatial and temporal resolution and a multi-modal spectroscopic technique that expands on standard nuclear magnetic resonance (NMR) techniques to provide a direct measure the strength and distribution of spin-spin interactions. The beginning stages of implementing the quantum mechanical magnetic camera are presented, the characterization of the intrinsic noise in MTJs, the details of a highly sensitive probe we built, and the experimental techniques implemented to accurately measure such small signals. The direct measure of spin-spin interaction strength is demonstrated by probing 31P nuclear spins in the van der Waals antiferromagnet NiPS3, which enabled the detection of a sharp change in the hybridization strength of the 31P-31P dimer at the magnetic phase transition and the absence of any distribution in the 31P-31P interaction strength above the magnetic transition. The results obtained through application of this technique provide valuable insight into the nature of magnetic interactions in this material. Finally, results of standard NMR measurements of the van der Waals antiferromagnet CoNb3S6 are presented. These measurements provide insight into the nature of the complicated magnetic order in this material and on the origins of the anomalous Hall effect that arises in the antiferromagnetic phase.
- Notes:
- Thesis (Ph. D.)--Brown University, 2025
Citation
Bales, Calvin,
"Applications of Multi-Modal Spectroscopic Techniques for the Study of Magnetism in Strongly Correlated Materials"
(2025).
Physics Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://repository.library.brown.edu/studio/item/bdr:wm2ab4t2/
