X-ray Absorption Study of Structural Coupling in Photomagnetic Prussian Blue Analogue Core@Shell Particles

X-ray absorption spectroscopy experiments of core@shell, photomagnetic, and Prussian Blue analogue heterostructures obtain the local structure around the magnetic transition-metal ions before and after illumination. Two samples, containing nickel hexacyanochromate (Ni–Cr) and cobalt hexacyanoferrate (Co–Fe) in Ni–Cr@Co–Fe and Co–Fe@Ni–Cr geometries, were studied. Both materials display the well-known photoinduced valence tautomerism for Co–Fe, accompanied by a large change in cobalt to nitrogen distances. Furthermore, these experimental results show a structural coupling of the photoactive Co–Fe layer to the passive Ni–Cr layer. Finally, the strain across the heterostructured interface in Co–Fe and Ni–Cr containing core@shell models is investigated with simulations that use custom potentials derived from density functional theory calculations.