Heading to photoswitchable magnets

Abstract

In the review, available strategic approaches to the photomodulation of magnetic properties in molecular hybrid substances combining magnetic and optical properties have been considered. The developed approaches have been divided in two groups, namely, photocontrol of intra- and inter-molecular magnetic coupling and the effect of a photochromic sub-lattice on bulk behavior of a molecular magnet. In the frame of the first approach, the following has been considered: photoinduced phase transitions with the charge transfer and the change of a spin state of magnetic centers; photoswitching of intra-molecular exchange interactions between magnetic centers linked by a photochromic bridge; generation of high-spin organic molecules forming high-spin groups due to inter-molecular exchange interactions. In the frame of the second approach, hybrid polyfunctional compounds combining magnetic and photochromic sub-lattices in the same crystalline lattice, as well as intercalation of organic photochromes in cavities or inter-layer space of an organic magnetic (or vice versa) have been discussed. Creation of such materials allows not only unification of several functions in one lattice (this being important for reducing the size of the element base in devices), but also control and modification of these properties through synergetic effects. Fundamental results suggest that new materials for various practical applications can be created using crystal chemical design.