Photo-induced low temperature structural transition in the “114” YBaFe4O7 oxide

•YBaFe4O7 undergoes a tetragonal to monoclinic transition below 190 K.•A photoinduced structural transition is observed below 190 K.•Melting of charge order is proposed to explain the photoinduced transition.

Synchrotron irradiation of the oxide YBaFe4O7.0 below 190 K converts the low temperature monoclinic structure to a higher symmetry tetragonal form analogous to the room temperature structure. This photo-induced metastable tetragonal form is stable even in the absence of irradiation over the range 4–60 K, however, above 60 K the photo-transition is reversible. These structural phenomena are correlated to the magnetic behaviour of this system, suggesting possible spin-lattice coupling. A scenario explaining the low temperature photo-induced transition is proposed, based on the different distributions of the valence electrons in the iron sub-lattice of the monoclinic and tetragonal phases.