Photomagnetic and structural studies of Prussian blue analogue CoFe@CoCr core@shell heterostructures

The photomagnetic and structural properties of core@shell nanostructures of Prussian blue analogues, Rb$_{0.24}$Co[Fe(CN)$_6$]$_{0.74}$@K$_{0.10}$Co[Cr(CN)$_6$]$_{0.70} \cdot n$H$_2$O, with different shell thicknesses have been studied as a function of temperature and under white light irradiation.\footnote{O. N. Risset \emph{et al}., J. Am. Chem. Soc. (2014) DOI:10.1021/ja5084283.} The nature of the charge transfer induced spin transition (CTIST) of the core was affected by the presence of the shell. Specifically, while a continuous and hysteretic CTIST was observed in the bare cores, a discontinuous and non-hysteretic behavior was observed for the core@shell systems. In addition, the core@shell nanoparticles show light-induced magnetization changes radically different from the bare cores. These changes were modeled as a combination of the expected light-induced magnetism change in the cores and a modification of the magnetism in a region of the shell close to the interface, where the depth of the modified region was found to be about 25~nm for all shell thicknesses investigated.