Evidence for Interface-Induced Strain and Its Influence on Photomagnetism in Prussian Blue Analogue Core–Shell Heterostructures, RbaCob[Fe(CN)6]c·mH2O@KjNik[Cr(CN)6]l·nH2O

Abstract

A series of photomagnetic coordination polymer core–shell heterostructures, based on the light-switchable Prussian blue analogue RbaCob[Fe(CN)6]c·mH2O (RbCoFe-PBA) as the core and the ferromagnetic KjNik[Cr(CN)6]l·nH2O (KNiCr-PBA) as the shell, was studied using powder X-ray diffraction, down to 100 K, and magnetometry, down to 2 K, to investigate the influence of the shell thickness on light-induced magnetization changes and gain insight into the mechanism. The core material is known to undergo a charge-transfer-induced spin transition (CTIST), and synchrotron powder diffraction was used to monitor structural changes in both the core and the shell associated with the thermally and optically induced CTIST of the core. Significant lattice contraction in the RbCoFe-PBA core upon cooling through the high-spin to the low-spin state transition near ∼260 K induces strain on the KNiCr-PBA shells. This lattice strain in the shell can be relieved either by thermal cycling back to high temperature or by using light...