Direct observation of low-temperature superstructure in spin- and charge-frustrated ferrite YFeO

Horibe, Yoichi*; Ikeda, Naoshi*; Yoshii, Kenji  ; Mori, Shigeo*

The low-temperature superstructure of YFeO was carefully investigated by transmission electron microscopy. We found that the unique superstructure at about 100 K is characterized by /14 2/7 1/14-type superlattice reflection spots, suggesting the presence of charge reordering process. The low-temperature high-resolution images clearly show superlattice modulations in Y-O layers as well as Fe-O layers. The modification of intra-bilayer charge interactions due to lattice distortions in Y-O layers is discussed to play a crucial role in the stabilization of long-periodic superstructures at low temperatures.