Soft X-ray spectroscopies usually average the observed response of a sample across the entire illuminated area. This restricts the obtainable information, especially if the sample is inhomogeneous (either because of electronic domain formation or patterning on the micro- and nanoscale). Formation of electronically distinct domains has been observed for various quantum materials. A complete understanding thus necessitates a domain-resolved experimental approach.
We demonstrate the implementation of an experimental setup, build around an off-axis Fresnel zone plate, which enables imaging X-ray absorption spectroscopy and resonant inelastic X-ray scattering with a current spatial resolution down to 1.8µm. The zone plate, located between sample and detector, disperses X-rays scattered from the sample and also images the sample along the direction perpendicular to the dispersion. Incident X-rays are focused to a 1mm long line such that excitation spectra from each point along the line are measured in-parallel.
In a microstructured VO2 thin-film, we find that the structure edges undergo the insulator-metal transition earlier than the centers, hinting at facilitated strain release. We believe that the observed effects apply in general to patterned films of quantum materials and provide a tool for adequate experimental studies.
Reference: J.O. Schunck et al. Optica 8(2), 2021