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|Type:||Artigo de periódico|
|Title:||B1g Mode Softening In Fef2|
|Abstract:||Experiments are reported for the temperature dependence of phonon Raman scattering in FeF2. The B1g phonon exhibits anomalous frequency softening with decreasing temperature for temperatures in the range TN=78-340 K. This softening is less marked for temperatures below TN because of spin-lattice effects resulting from the antiferromagnetic ordering. In the higher-temperature region the square of the B1g-phonon frequency is proportional to temperature, which is suggestive of a virtual structural phase transition. However, consideration of other work on the pressure dependences of the Raman-active modes in similar compounds leads us to conclude that the mode softening results largely from the lattice thermal contraction. This contraction disproportionally influences the forces between nearest-neighbor fluorine ions in adjacent planes perpendicular to the c axis. © 1983 The American Physical Society.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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