skip to main content

Search for: All records

Creators/Authors contains: "Goodge, Berit H."

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. As a real-space technique, atomic-resolution STEM imaging contains both amplitude and geometric phase information about structural order in materials, with the latter encoding important information about local variations and heterogeneities present in crystalline lattices. Such phase information can be extracted using geometric phase analysis (GPA), a method which has generally focused on spatially mapping elastic strain. Here we demonstrate an alternative phase demodulation technique and its application to reveal complex structural phenomena in correlated quantum materials. As with other methods of image phase analysis, the phase lock-in approach can be implemented to extract detailed information about structural order and disorder, including dislocations and compound defects in crystals. Extending the application of this phase analysis to Fourier components that encode periodic modulations of the crystalline lattice, such as superlattice or secondary frequency peaks, we extract the behavior of multiple distinct order parameters within the same image, yielding insights into not only the crystalline heterogeneity but also subtle emergent order parameters such as antipolar displacements. When applied to atomic-resolution images spanning large (~0.5 × 0.5 μ m 2 ) fields of view, this approach enables vivid visualizations of the spatial interplay between various structural orders in novel materials.
    Free, publicly-accessible full text available April 1, 2023
  2. The unconventional superconductivity in Sr 2 RuO 4 is infamously susceptible to suppression by small levels of disorder such that it has been most commonly studied in extremely high-purity bulk crystals. Here, we harness local structural and spectroscopic scanning transmission electron microscopy measurements in epitaxial thin films of Sr 2 RuO 4 to disentangle the impact of different types of crystalline disorder on superconductivity. We find that cation off-stoichiometry during growth gives rise to two distinct types of disorder: mixed-phase structural inclusions that accommodate excess ruthenium and ruthenium vacancies when the growth is ruthenium-deficient. Several superconducting films host mixed-phase intergrowths, suggesting this microstructural disorder has relatively little impact on superconductivity. In a non-superconducting film, on the other hand, we measure a high density of ruthenium-vacancies [Formula: see text] with no significant reduction in the crystallinity of the film. The results suggest that ruthenium vacancy disorder, which is hidden to many structural probes, plays an important role in suppressing superconductivity. We discuss the broader implications of our findings to guide the future synthesis of this and other layered systems.
    Free, publicly-accessible full text available April 1, 2023
  3. Free, publicly-accessible full text available May 1, 2023
  4. Tomographic spectroscopy reveals how the properties of topological materials can be engineered at interfaces.
    Free, publicly-accessible full text available February 4, 2023
  5. Thin-film electrostatic engineering is used to uncover a hidden antiferroelectric phase.
    Free, publicly-accessible full text available February 4, 2023
  6. The recent observation of superconductivity in N d 0.8 S r 0.2 N i O 2 has raised fundamental questions about the hierarchy of the underlying electronic structure. Calculations suggest that this system falls in the Mott–Hubbard regime, rather than the charge-transfer configuration of other nickel oxides and the superconducting cuprates. Here, we use state-of-the-art, locally resolved electron energy-loss spectroscopy to directly probe the Mott–Hubbard character of N d 1 − x S r x N i O 2 . Upon doping, we observe emergent hybridization reminiscent of the Zhang–Rice singlet via the oxygen-projected states, modification of the Nd 5d states, and the systematic evolution of Ni 3d hybridization and filling. These experimental data provide direct evidence for the multiband electronic structure of the superconducting infinite-layer nickelates, particularly via the effects of hole doping on not only the oxygen but also nickel and rare-earth bands.