Effect of film thickness on the photoinduced decrease in magnetism for thin films of the cobalt iron Prussian blue analogue Rb0.7Co4[Fe(CN)6]3.0

Films of the photomagnetic Prussian blue analogue Rb0.7Co4(Fe(CN)6)3.0(Co–Fe PBA) were deposited onto a Melinex® substrate using two different multiple sequential adsorption methods. Film thickness, measured using atomic force microscopy, was controlled by the number of deposition cycles. The photoinduced magnetism known for the bulk Co–Fe PBA at low temperatures is also seen in the thin films, although the response is anisotropic. A photoinduced increase in magnetization is observed when the film is parallel (∥) to the applied magnetic field (HE), while a photoinduced decrease is observed when the film is perpendicular (⊥) to a weak HE. The relationship between the film thickness and the photoinduced decrease in magnetization is explored in this article. The photoinduced decrease is observed for films less than ∼200 nm thick. The behavior is explained by invoking a dipolar interaction between primordial ferrimagnetic domains and the photoswitchable pairs arrayed in the quasi-2D thin film.

Graphical abstractThe photomagnetic behavior of thin films of the Co–Fe Prussian blue analogue is investigated as the films transition from a quasi-two-dimensional system to a three-dimensional system with increasing thickness. A quasi-two-dimensional film with thickness less than ∼200 nm is needed to observe the photoinduced decrease in magnetization unique to thin films of this material.Figure optionsDownload full-size imageDownload as PowerPoint slide