Optically induced magnetism in cobalt iron cyanide

Abstract

Theoretical studies on the recently observed optically induced magnetization in nanoparticles of ${\mathrm{K}}_{0.2}{\mathrm{Co}}_{1.4}{\left[\mathrm{Fe}\right(\mathrm{CN})\mathrm{}}_6{]\mathrm{\cdot }6.9\mathrm{H}}_2\mathrm{O}$ have been carried out by simulating the solid with representative clusters. Our studies, performed within the density-functional formalism, show that the ground state is supplemented by several excited states with varying spin multiplicities. Illumination of the solid by light results in excitations to different states depending on the photon energy. In particular, it is shown that while red light enhances the magnetization, blue light reduces it—in agreement with the observed changes.