Raman scattering study of the three structural phases of KMnF3
- 7 August 1974
- journal article
- Published by IOP Publishing in Journal of Physics C: Solid State Physics
- Vol. 7 (15) , 2729-2744
- https://doi.org/10.1088/0022-3719/7/15/022
Abstract
The Raman spectra of the three phases of KMnF3 have been measured and a detailed group theoretical analysis has been carried out in order to identify the observed peaks. The results for the intermediate temperature phase are consistent with a tetragonal structure of D4h18 symmetry but the results for the low-temperature phase do not unambiguously determine the crystal structure. Particular attention was paid to the temperature-dependent modes. The soft modes associated with the upper phase transition were fitted to the response functions for a damped simple harmonic oscillator and for a model including damping by phonon density fluctuations. The results favour the latter model and suggest that non-classical critical fluctuations play an important role near the upper phase transition.Keywords
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