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Novel opportunities are emerging at third-generation synchrotron x-ray facilities ushered in by their coherence upgrade as well as at x-ray free-electron-laser facilities worldwide. These sources afford researchers to go far beyond ‘average’ reciprocal-space investigations by x-ray diffraction, which has been a mainstay methodology of research on quantum materials. In this talk contemporary research efforts to exploit multitude of contrasts accessible via diffraction germinating a novel imaging modality called dark field x-ray microscopy (DFXM) [1] and its outlook at future sources (e.g., APS-U) are presented. DFXM technique provides real-space images of ‘mesoscale’ features [2-4] that give rise to deviations from an average order. In DFXM, a diffracted beam from an ordered material is used to form a two-dimensional full-field image of these features by passing it through an x-ray objective lens. Mesoscale information is encoded on a crystal Bragg peak, a super-lattice (e.g., due to charge, magnetic, or orbital order) peak, or an epitaxial-film peak, in the form of intensity contrasts, revealing an incisive real-space picture over many orders-of-magnitude in length scales. In this talk, some recent illustrative cases are reviewed along with state-of-the-art technical advances of this methodology. Examples include a role of local actors across a magneto-structural phase transition [2], a set of imaging studies of three dimensionally ordered charge-density waves in superconductors, a search for long-range modulations below a nematic transition, and an exploration of neomorphism in metal-insulator-transition based memristor devices. Finally, new directions to leverage increased coherence in DFXM studies are sketched.

Work performed at the Advanced Photon Source was supported by the DOE, under Contract No. DE-AC02-06CH11357

▶ References

[1] Zhi Qiao, Xianbo Shi, Peter Kenesei, Arndt Last, Lahsen Assoufid, and Zahir Islam, “A large field-of-view high-resolution hard x-ray microscope using polymer optics”, Rev. Sci. Instrum. 91, 113703 (2020); https://doi.org/10.1063/5.0011961

[2] Jayden Plumb, Ishwor Poudyal, Rebecca L. Dally, Samantha Daly, Stephen D. Wilson, Zahir Islam, “Dark Field X-ray Microscopy Below Liquid-Helium Temperature: The Case of NaMnO2,” Materials Characterization 204, 113174 (2023).

[3] Elliot Kisiel, Ishwor Poudyal, Peter Kenesei, Mark Engbretson, Arndt Last, Rourav Basak, Ivan Zaluzhnyy, Uday Goteti, Robert Dynes, Antonino Miceli, Alex Frano, Zahir Islam, “Full-Field Nanoscale X-ray Diffraction-Contrast Imaging using Direct Detection”, arXiv:2212.07303 physics.ins-det cond-mat.mes-hall (2022)

[4] Omar Abulshohoud, Ishwor Poudyal, Jessica McChesney, Zhan Zhang, Zhi Qiao, Ulrich Welp, Zahir Islam, “A general method for multiresolutional analysis of mesoscale features in dark-field x-ray microscopy images”, arXiv:2210.15757 cond-mat.mtrl-sci (2022)

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