Pressure-induced amorphization ofCuFeS2studied byFe57nuclear resonant inelastic scattering

Abstract

Static and dynamic structural properties of $\mathrm{Cu}\mathrm{Fe}{\mathrm{S}}_{2}$ under high pressure were investigated by x-ray diffraction and $^{57}\mathrm{Fe}$ nuclear resonant inelastic scattering. Using x-ray diffraction, we obtained evidence that a pressure-induced amorphization occurs at about $6.3\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$, which represents a metal-insulator transition. Although partial phonon densities of states extracted from $^{57}\mathrm{Fe}$ nuclear resonant inelastic scattering spectra are similar in the two phases, the derived thermodynamical parameters show anomaly at the transition. The results of extracted partial phonon densities of states and ab initio phonon calculations indicate that this pressure-induced amorphization is caused by anomalous pressure dependences of the lower optical phonon branches and the initial slopes of the transverse acoustic phonon branches.