Figure 4
(a) Schematic representation of the crystal structure for the Fe2+ (black circles) and Fe3+ (gray circles) ordering in YbFe2O4, as expected from the SHG and neutron diffraction measurements. The dotted lines represent the monoclinic unit cell and the red and green colored circles represent the locations of O and Yb, respectively. The yellow arrows denote the polarization direction, which is tilted 16.5° from the [001]h. (b) Projection of the crystal structure onto the (010)m plane, where the polarization tilt direction can be more clearly resolved. (c) Schematic view of the polarization switching due to electron hopping within the W-layers. The possible directions of electron (e−, small blue circles) hopping are labeled with small blue arrows. The large orange and blue arrows represent polarization switching. There crystal structure was drawn by VESTA 3 software27.
