Publication Date

2024

Document Type

Dissertation/Thesis

First Advisor

Xiao, Zhili

Degree Name

Ph.D. (Doctor of Philosophy)

Legacy Department

Department of Physics

Abstract

This dissertation investigates the magnetotransport properties of topological semimetals, specifically focusing on the Dirac semimetal TaCo2Te2 and the Weyl semimetal Co3Sn2S2. In TaCo2Te2, I observed extremely large magnetoresistance that violates Kohler’s rule. Extended Kohler’s rule can be applied with a calculation of Hall factor at low temperatures. I also explored the applicability of the two-band and four-band models of carrier analysis and correlate the region where Kohler’s rule is obeyed to the four-band model. In Co3Sn2S2, I explored the angle-dependent anomalous Hall effect (AHE) near the Kagome plane, revealing a tunable AHE under applied fields and an abrupt disappearance of AHE at low fields along the Kagome plane. My findings suggest the presence of an antiferromagnetic phase and show that the hysteresis loops are influenced by field orientation, even at low temperatures. To gain a better understanding of the transport properties, magnetic structures were studied using magneto-optical imaging, indicating the importance of domain wall pinning in exchange bias effects. I calculated the temperature-dependent anisotropy constant, domain wall energy, and width from magnetization curves. Overall, this dissertation elucidates magneteotransport properties of two types of topological semimetals.

Extent

105 pages

Language

en

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

Download

Share

COinS