Twisted light-matter interaction and coherent scattering with X-rays

Recent technological breakthroughs in synchrotron radiation and XFEL facilities have revolutionized our understanding of dynamical and emergent behavior at the nanoscale by harnessing charge, lattice, spin, and orbital degrees of freedom in condensed matter systems. In this presentation, I will discuss our group's advancements in developing coherent scattering and diffractive imaging techniques [1], which are now at the forefront of exploring hard and soft condensed matter systems [2-4]. These techniques, notably Bragg coherent diffractive imaging, x-ray photon correlation spectroscopy, and  x-ray magnetic dichroism leverage beam coherence to achieve volumetric three-dimensional imaging at unprecedented sub-nanometer resolutions and explore dynamic phenomena within sub-millisecond timeframes. Such capabilities are critical in understanding and developing advanced materials and technologies.

Simultaneously, the emergence of chiral phenomena in the lattice, charge, spin, and orbital degrees of freedom-characterized by their unique absence of standard inversion, mirror, or other roto-inversion symmetries-presents both challenges and opportunities. These materials exhibit distinctive interactions with light, leading to phenomena such as molecular optical activity, chiral photonic waveguides, and valley-specific light emissions, which are pivotal in the burgeoning fields of photonic and spintronic devices. I will address how novel x-ray probes can be leveraged to unravel these properties and their implications for future technological applications. A significant focus of this talk is the exploration of new avenues in research, particularly the shift from conventional methods to more innovative approaches in studying these chiral materials. Inspired by structured optical beams, the potential of coherent scattering techniques utilizing twisted x-ray beams will be examined. This promising direction not only offers higher spatio-temporal resolution but also opens the door to previously unattainable insights into condensed matter systems.

References

Coherent diffractive imaging with twisted X-rays: Principles, applications, and outlook, N. Nazirkar, et al.    Appl. Phys. Rev. 11, 021302 (2024) Enhanced Piezoelectric Response at Nanoscale Vortex Structures in Ferroelectrics. X. Shi et al. ACS Appl. Mater. Interfaces 2024, 16, 6, 7522–7530 (2024) Three-dimensional imaging of vortex structure in a ferroelectric nanoparticle driven by an electric field. Karpov et al, Nature Communications volume 8, Article number: 280 (2017) Giant pyroelectricity in nanomembranes. Jian et al, Nature volume 607, pages 480–485 (2022)