Abstract
We present results from light scattering experiments on tetragonal FeS with the focus placed on lattice dynamics. We identify the Raman active and phonon modes, a second order scattering process involving two acoustic phonons, and contributions from potentially defect-induced scattering. The temperature dependence between 300 and 20 K of all observed phonon energies is governed by the lattice contraction. Below 20 K the phonon energies increase by 0.5–1 , thus indicating putative short range magnetic order. Along with the experiments we performed lattice-dynamical simulations and a symmetry analysis for the phonons and potential overtones and find good agreement with the experiments. In particular, we argue that the two-phonon excitation observed in a gap between the optical branches becomes observable due to significant electron-phonon interaction.
2 More- Received 12 December 2017
DOI:https://doi.org/10.1103/PhysRevB.97.054306
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