Graduate Thesis Or Dissertation

 

Electronic Structure of CuMnAs, an Antiferromagnetic Dirac Semimetal Candidate, and Progress Towards ARPES on Optically Driven Superconductivity Public Deposited

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https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/r781wh543
Abstract
  • The field of spintronics has long sought to make better computing devices by harnessing the electron spin. Meanwhile the growing field of topology in electronic band structures has been at the forefront of many recent developments in our basic understanding of materials physics. CuMnAs is at the intersection of these two fields, combining control over Antiferromagnetic (AFM) order with novel changes in electron band structure and topology. Because the latter is mediated by the AFM order, CuMnAs is predicted to host a new topological metal insulator transition that can be controlled at THz speeds. Thus, CuMnAs opens paths to faster [𝒪(1000x)] computing devices and controlled studies of ultrafast topology changes. My work provides the first direct test of the density functional theory that underlies the above predictions in CuMnAs, including measuring the electronic band structure in CuMnAs using angle-resolved photoemission spectroscopy (ARPES).

    For over a hundred years, physicists have dreamt of a room temperature superconductor, which would change the world through numerous technologies. Yet, to this day, room temperature superconductivity remains an unrealized dream. However, in recent years, studies have found signatures in THz reflectivity measurements of a transient superconducting state at, or even above, room temperature. The state is induced by excitation with an intense mid-infrared, ultrafast laser pulse. Because the state is so short lived [𝒪(ps − ns)], the primary signatures of superconductivity—0 DC resistance and the Meissner-Ochsenfeld effect—have not been measured conclusively. Therefore, I have set out to measure the transient state using time-resolved ARPES, which would have other signs of superconductivity and could even directly test some of the alternate hypotheses and proposed theories. While my measurements will come after the completion of this thesis, I will discuss my work to improve our measurement system, enabling the future measurements.

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  • 2023-05-10
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  • 2024-01-16
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