Crosses and Flowers: Investigating superstructures in the high-Tc superconductor La(2–x)Sr(x)CuO(4+y)
PhD defence by Pia Jensen Ray
Assessment Committee
Professor Brian Møller Andersen, Niels Bohr Institutet, University of Copenhagen (Chairperson)
Professor Elizabeth Blackburn, University of Lund
Assistant Professor (tenured) Machteld Kamminga, University of Utrecht
Supervisors
Professor Kim Lefmann
Department
Niels Bohr Institute
Place
Building: Niels Bohr Building, Room: Margrethe Bohr Salen, Jagtvej 132, 2200 Copenhagen
Email address to gain access to the thesis: pia@pjray.dk.
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Short description of the thesis
High-temperature superconductivity remains one of the great unsolved puzzles of condensed matter physics. This thesis focuses on La(2-x)Sr(x)CuO(4+y), a family of cuprate superconductors doped in two ways, through strontium substitution and excess interstitial oxygen.
Superstructures in superoxygenated samples spanning multiple strontium-doping levels were mapped using neutron and X-ray diffraction instruments at several research facilities. Measurements spanned various temperatures, from a few kelvin to room temperature, revealing a rich landscape of ordering patterns that shift with doping. These patterns may be linked to how the extra oxygen atoms arrange themselves beyond the crystal's basic repeating unit.
This defence presents an overview of this work, one contribution to a puzzle shaped by many scientists, building on what came before and offering a foundation for what comes next.