Crystallographical and morphological changes in charge-ordering transition of RFe2O4 (R: Y, Lu) investigated by transmission electron microscopy

Temperature dependence of charge-ordered crystal structures and domain structures in RFe2O4 (R: Y and Lu) was investigated by energy-filtered transmission electron microscopy, combined with conventional transmission electron microscopy. The presence of three-dimensional to two-dimensional charge ordering transition were observed in both YFe2O4 and LuFe2O4 on heating. Furthermore, real-space images obtained with the energy-filtered transmission electron microscopy revealed that YFe2O4 has less anisotropic nanometer-scale charge-ordered domains than LuFe2O4. These findings in RFe2O4 indicate the importance of the interchange interactions between Fe-O bilayers in addition to those within bilayers in the structural phase transitions associated with charge ordering in this system.

Automated summary

Temperature dependence of charge-ordered crystal structures and domain structures in RFe2O4 (R: Y and Lu) was studied using energy-filtered transmission electron microscopy and conventional transmission electron microscopy. The results showed a transition from three-dimensional to two-dimensional charge ordering in both YFe2O4 and LuFe2O4 upon heating, with YFe2O4 exhibiting less anisotropic nanometer-scale charge-ordered domains compared to LuFe2O4. The findings indicate the significance of interchange interactions between Fe-O bilayers in addition to those within bilayers in the structural phase transitions associated with charge ordering in RFe2O4.