Lowering of the spatial symmetry at the γ → α phase transition in cerium

摘要: Using time-differential perturbed angular correlation spectroscopy we have measured the electric field gradient (EFG) at $^{111}\text{C}\text{d}$ probe nuclei in solid Ce a pressure range up to 8 GPa. Covering various allotropic phases of Ce, find that value EFG cubic $\ensuremath{\alpha}$ phase is almost four times larger than $\ensuremath{\gamma}$ and close values noncubic ${\ensuremath{\alpha}}^{\ensuremath{'}}$ ${\ensuremath{\alpha}}^{\ensuremath{''}}$. These results together with differences time modulation spectra are interpreted as evidence for quadrupolar electronic charge-density ordering symmetry lowering $\ensuremath{\gamma}\ensuremath{\rightarrow}\ensuremath{\alpha}$ transition while lattice remains face-centered cubic.