Coherent Domain Growth under Photo-Excitation in a Prussian Blue Analogue

Abstract

We have investigated the structural properties of the photo-induced metastable phase of a Prussian blue analogue (Na 0.42 Co[Fe(CN) 6 ] 0.78 ·4.64H 2 O), which shows the photo-magnetization phenomenon, as revealed by means of the high angle-resolved synchrotron-radiation X-ray powder diffraction technique. We have found that (1) the structural domain size is larger than the quenched high-temperature phase and (2) the lattice constant a (=10.287(1) Å) is larger than that of the quenched phase ( a =10.187(3) Å). These observations indicate that photo-excitation coherently increases the size of the photo-induced metastable region even at low temperature (91 K≪ T c ).