Yi, MingKono, Junichiro2024-01-222024-01-222023-082023-09-15August 202Yue, Ziqin. "Surface Modification of Quantum Materials." (2023) Master's thesis, Rice University. https://hdl.handle.net/1911/115348https://hdl.handle.net/1911/115348EMBARGO NOTE: This item is embargoed until 2024-08-01The tuning of surface electronic structure in quantum materials has emerged as an important research direction with broad implications for both fundamental physics as well as applications. Here we carried out angle-resolved photoemission spectroscopy to characterize the continuous evolution of the electronic band structures in a prototypical three-dimensional topological insulator, Bi2Se3, and a van der Waals ferromagnetic semiconductor, Cr2Ge2Te6, using different approaches of in-situ surface modification. In Bi2Se3, by active hydrogen etching, we demonstrate the gradual removal of Se atoms and the formation of Bi bilayers that directly result in the spatial tuning of the topological surface states. In Cr2Ge2Te6, by surface alkali metal dosing, we observe the appearance and tuning of a Van Hove singularity in the electronic structure and subsequent renormalization of the conduction band, suggesting the tuning of surface charge carriers as a way to modify electronic correlations in 2D materials.application/pdfengCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.Surface ModificationTopological Materialsvan der Waals MaterialsThesis2024-01-22