X-Ray Studies of Phonon Softening inTiSe2

Abstract

The charge-density-wave transition in $\mathrm{TiSe}{}_2$, which results in a commensurate $(2\times 2\times 2)$ superlattice at temperatures below $\sim 200\mathrm{K}$, presumably involves softening of a zone-boundary phonon mode. For the first time, this phonon-softening behavior has been examined over a wide temperature range by synchrotron x-ray thermal diffuse scattering.