Polarized Raman scattering and lattice eigenmodes of antiferromagnetic NdFeO3

The first‐ and second‐order Raman‐active phonons in the orthorhombic Pbnm NdFeO3 single crystals were studied by means of polarized Raman scattering and lattice dynamics computations (LDC). The zone‐center phonons of Ag symmetry were distinguished from the B1g eigenmodes by performing polarized Rama...

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Bibliographic Details
Published in:Journal of Raman spectroscopy 2008-07, Vol.39 (7), p.842-848
Main Authors: Singh, Manoj K., Jang, Hyun M., Gupta, H. C., Katiyar, Ram S.
Format: Article
Language:English
Subjects:
Cations
force constants
Iron
lattice dynamics
Lattices
Oxygen atoms
Phonons
Raman scattering
Raman spectroscopy
rare-earth orthoferrites
Symmetry
Vibration
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Summary:The first‐ and second‐order Raman‐active phonons in the orthorhombic Pbnm NdFeO3 single crystals were studied by means of polarized Raman scattering and lattice dynamics computations (LDC). The zone‐center phonons of Ag symmetry were distinguished from the B1g eigenmodes by performing polarized Raman scattering experiments using two parallel polarization configurations, X′(ZZ)X′ and Z(X′X′)Z. With the help of LDC, we were able to assign most of the observed Raman‐active modes, including phonons of B2g and B3g symmetry. The LDC results indicated that among the 16 force constants employed, the one corresponding to the stretching vibration between the central Fe cation and the axial oxygen atom in a FeO6 octahedron unit had the largest value. This suggests that the B‐site Fe cation is more tightly bound to the axial O1 ion than the other two equatorial O2 ions. It was further shown that at higher wavenumbers, the displacement of oxygen atoms contributed dominantly to the zone‐center vibrations. Copyright © 2008 John Wiley & Sons, Ltd.
ISSN:0377-0486
1097-4555
DOI:10.1002/jrs.1923