Seminar :: January 29 :: Bradford Barker

The characterization of defect states in the novel defected two-dimensional monolayer material  WS2:Co@S

Bradford Barker

Department of Physics
University of California, Merced

Abstract


Atomic-scale defects in two-dimensional solids have exciting potential applications in high-density memory devices, quantum information systems, and single-atom catalysts. With recent experimental realization of methods to reliably create single sulfur-site vacancies in the two-dimensional WS2 crystal, we consider the example defect of a single cobalt atom substituted at that sulfur vacancy site. Particularly, we look at the electronic structure and atomic geometry of this defected system as computed with density functional theory, and we compare the computed electronic states near the defect with that observed with scanning tunneling spectroscopy measurements by our collaborators.

Bio

Brad grew up in Florida and completed his bachelors in physics and in mathematics from the University of Florida. His dissertation work at the University of California, Berkeley with Prof. Steven G. Louie was on first-principles electronic structure and optical properties of materials performed with calculations based on many-body perturbation theory (GW and GW/BSE). His previous postdoctoral work with Prof. David A. Strubbe at University of California, Merced was on developing the theory of first-principles calculations of electronic structure of open-shell systems, such as quantum defects in solids, via the Spin-Flip Bethe-Salpeter Equation. He now works since 2023 with Prof. Beth Nowadnick and Dr. Sinéad Griffin on theoretical calculations relevant to electronic control of spin states in magnetic dopant defects in ferroelectric oxide crystals. His personal hobbies include building, repairing, modifying, and sometimes even playing musical electronics and instruments.