ANALYSIS OF PHOTOINDUCED MAGNETIZATION IN A (CO, FE) PRUSSIAN BLUE MODEL

The electronic properties of a modified (Co, Fe) Prussian blue compoun d, which exhibits interesting photoinduced magnetic properties, are an alyzed. For band structure calculations we set realistic models (for t he ground and excited states) that involve interstitial potassium ions , crystal water, and lattice defects. The top of the ''t(2g)'' block c onsists mainly of Fe 3d orbitals, the low-lying ''e(g)(1)'' block Co 3 d, and the high-lying ''e(g)(2)'' block Fe 3d. Because of the influenc e of crystal water coordinating to the Co ion, the ''e(g)(1)''-block b ands split into two parts; one is the ''e(g)(1)(N)'' block originating from the Go-NC fragment and another the ''e(g)(1)(0)'' block from the Co-OH2 fragment. The energy of visible light causing the magnetizatio n enhancement is close to the computed ''t(2g)(Fe-based)-e(g)(l)(N)'' and ''t(2g)(Fe-based)-e(g)(1)(0)'' separations in the ground-state mod el. It is reasonable from DOS (density of states) analyses that irradi ation with visible Light causes an electron transfer from the Fe(II) t o the Co(III) ions, through which the magnetization is effectively enh anced. Such an electron transfer is not a d-d transition on the same m etal ion so that the Laporte rule may not be applied, or if applied, t his rule may be relaxed in the (Co, Fe) Prussian blue.