Single domain growth and charge ordering of epitaxial YbFe₂O₄ films

Abstract

YbFe2O4 is a charge-ordered ferroelectrics that exhibits coupling between magnetization and electric polarization near room temperature, and crystallizes in a rhombohedral structure (R3¯m). This study presents an attempt to fabricate...

Nonlinear Optical Properties in an Epitaxial YbFe2O4 Film Probed by Second Harmonic and Terahertz Generation

“…Like the YSZ substrate, the film shows a three-fold symmetry, although residues of a six-fold peak are observed owing to the crystalline domains (60 • domains). The ratio of the six-fold to the three-fold component is about 8%, which is smaller than that observed in other RFe 2 O 4 films reported so far [14,17], indicating a good crystallization of YbFe 2 O 4 film. The normal incident transmission spectrum (T(ω)) was measured using a Fourier transform interferometer in the mid-and near-infrared region (0.01-1.0 eV).…”

“…An important feature in the electronic structure of the YbFe 2 O 4 film has a larger spectral weight in the mid-infrared region than that of the single crystal of LuFe 2 O 4 [22] or YbFe 2 O 4 [23]. This discrepancy may be caused by the lattice mismatch between the film and the YSZ substrate [14]. This makes the electronic structure different from that in a single crystal of YbFe 2 O 4 , resulting in a reduction in the d-d transition energy and an increase in the spectral weight in the mid-infrared region.…”

“…We synthesized YbFe 2 O 4 thin film crystal on YSZ (111) single crystal substrate. The films were deposited using the RF magnetron sputtering; the details are described elsewhere [14]. Table 1 shows the O 2 partial pressure during sputtering and the retention time before deposition in which the substrate temperature is kept at ~1400 K. Conventional X-ray diffraction (XRD) and TEM measurements were performed to determine the crystallinity of the film.…”

“…To apply electronic ferroelectricity observed in a bulk YbFe 2 O 4 to future ferroelectric devices, thin film crystals have been fabricated [13][14][15][16][17]. Several studies have succeeded in the epitaxial growth of YbFe 2 O 4 thin films on various substrates, including yttriumstabilized zirconia (YSZ) [13][14][15], MgO [16], and α-Al 2 O 3 [17,18], whose structures are compatible with the hexagonal lattice of RFe 2 O 4 .…”

“…To apply electronic ferroelectricity observed in a bulk YbFe 2 O 4 to future ferroelectric devices, thin film crystals have been fabricated [13][14][15][16][17]. Several studies have succeeded in the epitaxial growth of YbFe 2 O 4 thin films on various substrates, including yttriumstabilized zirconia (YSZ) [13][14][15], MgO [16], and α-Al 2 O 3 [17,18], whose structures are compatible with the hexagonal lattice of RFe 2 O 4 . Furthermore, based on transmission electron microscopy (TEM) observations, Fujii et al [14,17] first discovered that the resulting YbFe 2 O 4 films have a superlattice structure owing to the order of Fe ions having the same three-fold periodicity as single crystals [4,19].…”