Photomagnetism
Photomagnetism (photomagnetic effect) is the effect in which a material acquires (and in some cases loses) its
Mechanism
The magnetisation and demagnetisation (where not demagnetised thermally) occur through intermediate states
Prussian blue analogues
One of the most promising groups of molecular photomagnetic materials are Co-Fe Prussian blue analogues (i.e. compounds with the same structure and similar chemical make up to Prussian blue.) A Prussian blue analogue has a chemical formula M1-2xCo1+x[Fe(CN)6]•zH2O where x and z are variables (z may be zero) and M is an alkali metal. Prussian blue analogues have a face centre cubic structure.
It is essential that the structure be non-stoichiometric.[3] In this case the iron molecules are randomly replaced by water (6 molecules of water per replaced iron). This non-stoichiometry is essential to the photomagnetism of Prussian blue analogues as regions which contain an iron vacancy are more stable in the non-magnetic state and regions without a vacancy are more stable in the magnetic state. By illumination by the correct frequency one or another of these regions can be locally changed to its more stable state from the bulk state, triggering the phase change of the entire molecule. The reverse phase change can be accomplished by exciting the other type of region by the appropriate frequency.
See also
References
Further reading
- Ohkoshi, Shin-ichi; Tokoro, Hiroko (2012). "Photomagnetism in Cyano-Bridged Bimetal Assemblies". Accounts of Chemical Research. 45 (10): 1749–1758. PMID 22869535.
- Han, Jie; Meng, Ji-Ben (2009). "Progress in synthesis, photochromism and photomagnetism of biindenylidenedione derivatives". Journal of Photochemistry and Photobiology C: Photochemistry Reviews. 10 (3): 141–147. ISSN 1389-5567.