Photoinduced Magnetization of a Cobalt-Iron Cyanide

TLDR

Optical control of magnetic properties could enable magneto‑optical devices. The magnetization changes arise from an internal photochemical redox reaction. Red‑light illumination raises the critical temperature from 16 to 19 K and boosts magnetization below 16 K, effects that can be partially reversed by blue light and largely recovered by heating.

Abstract

Photoinduced magnetization was observed in a Prussian blue analog, K0.2Co1.4- [Fe(CN)6]·6.9H2O. An increase in the critical temperature from 16 to 19 kelvin was observed as a result of red light illumination. Moreover, the magnetization in the ferrimagnetic region below 16 kelvin was substantially increased after illumination and could be restored almost to its original level by thermal treatment. These effects are thought to be caused by an internal photochemical redox reaction. Furthermore, blue light illumination could be used to partly remove the enhancement of the magnetization. Such control over magnetic properties by optical stimuli may have application in magneto-optical devices.