  We have carried out an extensive phonon study on multiferroic GaFeO3 to
elucidate its dynamical behavior. Inelastic neutron scattering measurements are
performed over a wide temperature range, 150 to 1198 K. First principles
lattice dynamical calculations are done for the sake of the analysis and
interpretation of the observations. The comparison of the phonon spectra from
magnetic and non-magnetic calculations highlights pronounced differences. The
energy range of the vibrational atomistic contributions of the Fe and O ions
are found to differ significantly in the two calculation types. Therefore,
magnetism induced by the active spin degrees of freedom of Fe cations plays a
key role in stabilizing the structure and dynamics of GaFeO3. Moreover, the
computed enthalpy in various phases of GaFeO3 is used to gain deeper insights
into the high pressure phase stability of this material. Further, the volume
dependence of the phonon spectra is used to determine its thermal expansion
behavior.
