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We present structural, magnetic, and optical properties of multiferroic hexagonal YbFeO3 thin films, deposited on single crystal (001) Al2O3 and (111) ysz substrates by a magnetron sputtering system. Interestingly, the thermal stress affects YbFeO3 films on Al2O3 and ysz very differently. Although hexagonal-YbFeO3/Al2O3 films changed from a hexagonal to an orthorhombic phase due to annealing above 1000 °C, hexagonal-YbFeO3/ysz films remained mostly unaffected even after annealing at 1200 °C. The electronic excitations of the YbFeO3 thin films are dominated by Fe3+ d to d on-site electronic excitations as well as O 2p to Fe 3d, Yb 6s, and 5d charge-transfer excitations, and these excitations for hexagonal-YbFeO3 and orthorhombic-YbFeO3 thin films are distinctly different, consistent with the crystal field environments in the hexagonal and orthorhombic phases of YbFeO3. The room temperature energy band gaps of the hexagonal-YbFeO3 and orthorhombic-YbFeO3 thin films were measured to be ∼1.95 ± 0.05 eV and ∼2.40 ± 0.05 eV, respectively.
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Magnetic properties and spin reorientation of hexagonal HoFeO3 thin films
We present structural, magnetic, and optical properties of hexagonal HoFeO3/Al2O3 thin films deposited by Magnetron Sputtering. The x-ray diffraction patterns of HoFeO3 thin films show the c-planes of a hexagonal structure. The magnetization data display an antiferromagnetic transition temperature, TN∼120 ± 5 K and the magnetization-field hysteresis loops were measured below 100 K, confirming a weak ferromagnetism arising from a spin canting of the Fe3+ moments. The magnetization data also show an anomaly around ∼40 K due to a spin-reorientation transition caused by the Ho3+- Fe3+ interactions. We observed comparable magnetization along the ab plane and c axis although the spin canting of Fe3+ sites has a preferential component along the c axis, suggesting that the Ho3+- Fe3+ interactions dominate in the low temperature magnetic structures of hexagonal-HoFeO3. The observed electronic excitations at ∼2.29, 2.87, 3.82, 4.79, and 6.53 eV have been assigned to the Fe3+ d to d on-site as well as O 2p to Fe 3d, Ho 6s, and 5d charge-transfer excitations, respectively. The room temperature energy band gap of the hexagonal-HoFeO3 thin film was measured to be ∼1.99 ± 0.04 eV.
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- Award ID(s):
- 1406766
- PAR ID:
- 10215735
- Date Published:
- Journal Name:
- Thin solid films
- Volume:
- 723
- ISSN:
- 0040-6090
- Page Range / eLocation ID:
- 138596
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/https://doi.org/10.1016/j.tsf.2021.138596
