Abstract
We present the Raman scattering spectra of the compounds in a temperature range between 20 and 400 K. Although the crystal structures of these two compounds are both orthorhombic and very similar, they are not isostructural. The unit cell of ) is base-centered (primitive ), giving 18 (36) modes to be observed in the Raman scattering experiment. We have detected almost all Raman active modes, predicted by factor group analysis, which can be observed from the cleavage planes of these compounds. Assignment of the observed Raman modes of is supported by the lattice dynamics calculations. The antiferromagnetic long-range spin ordering in below leaves a fingerprint both in the and phonon mode linewidth and energy.
- Received 20 May 2014
- Revised 31 December 2014
DOI:https://doi.org/10.1103/PhysRevB.91.064303
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