Preparation of thin films of molecule-based magnets for optical measurements

Highlights: • Electrodeposition of Cr-Cr and Fe-Cr prussian blue analogue thin films. • High opacity caused by polycrystallinity, inherently rough surface and thickness. • Encapsulation with suitable adhesive and coverslip greatly improves transmittance. • Decreased opacity beneficial for transmission-based magneto-optical studies. Prussian blue analogues provide a useful model system for studying how the magnetic properties of molecular-based systems can be both perturbed and probed using light. However, the study of thin films of these materials using transmission-based optical techniques is limited due to their polycrystalline (or sometimes amorphous) morphology and inconsistent homogeneity, which act to scatter light. To address this shortcoming, thin films of Cr-Cr and Fe-Cr Prussian blue analogues have been encapsulated by suitable transparent adhesives to mitigate the effects of scatter, which would be of particular benefit in experiments that rely on the polarization of transmitted light being maintained. It is observed that transmittance is appreciably improved across the visible spectrum following encapsulation, reaching a tenfold increase at certain wavelengths. This is due to a combination of the reduction of air/film interfaces and refractive index-matching between adhesive and film.