Abstract
Phonon anomalies in intermediate valence compound TmSe have been studied using a three-body force rigid shell model (TRSM). Three-body interactions have been used because, due to valence fluctuations, the radii of rare-earth (RE) ion change significantly and therefore , the amount of overlap with neighboring chalcogen ions also changes. While the former fact results into the deformation of the RE ion, the latter fact gives rise to long-range three-body interactions between the transferred charges of the lattice. Actually, both facts influence the phonon dispersion curves (PDCs) strongly, particularly along the zone boundary. By using this model, the results of the calculation are found to agree well with the measured data for phonon dispersion as compared to the earlier results reported by using a three-body rigid ion model (TRIM). We also report Debye temperature variation and two-phonon IR/Raman spectra but these could not be compared with experimental data, as they are not available as yet.
Published Version
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