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Abstract:
We studied the vibrational dynamics of a single crystal of LaFe 4Sb 12
by three-axis inelastic neutron spectroscopy. The dispersion of phonons
with wave vectors q along [xx0] and [xxx] directions in the energy range
of eigenmodes with high amplitudes of lanthanum vibrations, i.e., at
planckomegalsim12 meV is identified. Symmetry-avoided anticrossing
dispersion of phonons is established in both monitored directions and
distinct eigenstates at high-symmetry points and at the Brillouin-zone
center are discriminated. The experimentally derived phonon dispersion
and intensities are compared with and backed up by ab initio lattice
dynamics calculations. Results of the computer model match well with the
experimental data.
