Transverse acoustic phonons of GaSb up to 7 GPa by inelastic neutron scattering

We have investigated the pressure dependence of the phonon dispersion of the transverse acoustic branches of GaSb by inelastic neutron scattering at 300 K. Frequency variations were measured along the [100], [110], and [111] directions up to 7 GPa, i.e. over the entire stability range of the zincblende structure. A strong softening is observed for zone boundary modes. These results are compared with published data on Ge up to 10 GPa as well as with first-principle calculations. We find generally good agreement between experiment and theory. The calculations reveal a strong pressure dependence of the Gruneisen parameters.