Light‐Induced Stored Information in Nanoparticles

Abstract

AbstractWe investigate here the consequence on light‐induced and thermally induced spin‐crossover (SCO) properties with particle size reduction from the macroscopic to microscale to nanoscale domains. Three samples with distinct particle sizes of the SCO coordination polymer [Fe(NCS)2(bpe)2] [bpe = 1,2‐bis(4′‐pyridyl)ethane] have been prepared by water‐in‐oil reverse micelle methods. Comparison of the magnetic properties with particle size reduction of these and the original macroscale slow‐grown crystals revealed that the spin transition becomes more gradual, more incomplete and concomitantly the transition temperature (T1/2) decreases – much like what is observed in metal dilution studies. Importantly, here, in the first photoinduced magnetic studies on a nanoparticle SCO system, we see that even on the nanoscale photoconversion of the low spin species to a metastable high‐spin state is possible. Furthermore, particle size reduction appears to have little effect on the temperature at which the stored photomagnetic information is erased. These results highlight that light‐induced SCO properties are governed by direct metal coordination environment (i.e., on the molecular scale), whereas, thermally induced magnetic properties rely more on crystal packing and ligand field effects.