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 in a pressure range up to 8 GPa. Covering various allotropic phases of Ce, we find that the value of the EFG in the cubic $\alpha$ phase is almost four times larger than in the cubic $\gamma$ phase and close to values in the noncubic phases ${\alpha }^{\prime }$ and ${\alpha }^{″}$. These results together with the differences in time modulation of the spectra are interpreted as evidence for quadrupolar electronic charge-density ordering and symmetry lowering at the $\gamma \to \alpha$ transition while the lattice remains face-centered cubic.

• Received 5 March 2010

DOI:https://doi.org/10.1103/PhysRevB.82.092102