1 option
Studies of Magneto-Optical Effects in Topological Insulators and Weyl Semimetals Using Terahertz and Optical Measurements Xingyue Han
- Format:
- Book
- Thesis/Dissertation
- Author/Creator:
- Han, Xingyue, author.
- Language:
- English
- Subjects (All):
- Physics.
- Electromagnetics.
- Optics.
- 0605.
- 0752.
- 0607.
- Local Subjects:
- Physics.
- Electromagnetics.
- Optics.
- 0605.
- 0752.
- 0607.
- Genre:
- Academic theses
- Physical Description:
- 1 electronic resource (144 pages)
- Contained In:
- Dissertations Abstracts International 87-03B
- Place of Publication:
- Ann Arbor : ProQuest Dissertations and Theses, 2025
- Language Note:
- English
- Summary:
- Topological materials such as topological insulators and Weyl semimetals host exotic electronic states that emerge from nontrivial band topology. A key scientific challenge is to experimentally probe the magneto-optical signatures of these materials, especially when time-reversal symmetry is broken. In such cases, magnetism can significantly influence the low-energy electrodynamics, giving rise to phenomena such as the anomalous Hall effect, spin-to-charge conversion, and circular dichroism. Understanding these effects is essential for both fundamental physics and the development of topological spintronic devices.In this dissertation, we employ terahertz (THz) and near-infrared (NIR) spectroscopies to investigate magnetic topological materials. We developed a time-domain THz transmission polarimetry system using photoconductive antennas, enabling precise measurements of polarization rotation in the 0.1-3.0 THz range. This system was applied to Cr-doped (Bi,Sb)2Te3, MnBi2Te4, and Co2MnGa, where we measured Faraday and Kerr effects and extracted complex optical conductivities. In parallel, we used THz emission spectroscopy based on electro-optic sampling to probe photocurrent dynamics. We observed helicity-dependent photocurrents in Co2MnGa and strong spin-to-charge conversion in magnetic/topological heterostructures. Additionally, circular dichroism microscopy was employed to study Eu2Ir2O7, a candidate magnetic Weyl semimetal with noncollinear antiferromagnetism, revealing significant circular dichroism attributed to a magnetic octupole moment.These measurements revealed several important findings. We demonstrated that the large anomalous Hall conductivity in Cr-doped (Bi,Sb)2Te3 and Co2MnGa originates from intrinsic Berry curvature effects. In MnBi2Te4, we observed a quantized anomalous Hall effect in thin films. In Overall, this work advances our understanding of the interaction between topology and magnetism and establishes time-domain THz and nonlinear optical spectroscopies as powerful tools for probing emergent phenomena in topological quantum materials
- Notes:
- Source: Dissertations Abstracts International, Volume: 87-03, Section: B.
- Advisors: Wu, Liang Committee members: Kikkawa, Jay; Kane, Charles; Mele, Eugene; Khoury, Justin
- Ph.D. University of Pennsylvania 2025
- Local Notes:
- School code: 0175
- ISBN:
- 9798291597484
- Access Restriction:
- Restricted for use by site license
The Penn Libraries is committed to describing library materials using current, accurate, and responsible language. If you discover outdated or inaccurate language, please fill out this feedback form to report it and suggest alternative language.