Lattice dynamics of 119Sn impurity in a bcc-Cr crystal.

The chromium crystal doped with 119 Sn isotope was studied using the
nuclear resonance inelastic x-ray scattering and first principles calculations. The Sn
partial phonon density of states was obtained for three temperatures that correspond
to different magnetic states of Cr. At all temperatures, the energy spectrum consists
of a broad band around 18 meV and a narrow peak at 43 meV. The additional peak
around 39 meV is observed only in the magnetically ordered phases, indicating the
influence of magnetic order in chromium on lattice dynamics. The partial phonon
density of states calculated with the antiferromagnetic order on Cr atoms show a very
good agreement with the experimental data. It is revealed that the high-energy peak is
lying above the phonon spectra of the pure bcc-Cr crystal. These are the local modes
with the increased energies due to a strongly reduced distance between Sn and the
nearest-neighbor Cr atoms.